Analysis and optimization of Polyhydroxyalkanoates production by environmental bacterial isolates from Nepal

Analysis and optimization of Polyhydroxyalkanoates production by environmental bacterial isolates from Nepal | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Analysis and optimization of Polyhydroxyalkanoates production by environmental bacterial isolates from Nepal Sandesh Adhikari, Saman Bhattarai, Roja Shrestha, Shikha Shree Shah, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5641446/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 25 Aug, 2025 Read the published version in BMC Microbiology → Version 1 posted 3 You are reading this latest preprint version Abstract The versatile non-biodegradable material plastic has significantly enhanced innovation, but its production heavily relies on fossil fuels and non-renewable resources, which causes severe pollution and ecosystem disruption, highlighting the urgent need for eco-friendly alternatives. Polyhydroxyalkanoates (PHA) are a class of bioplastics that offer a promising solution as biodegradable, environmentally compatible, and versatile biopolymer synthesized by microorganisms using various substrates, aiding in organic waste management. This study was aimed to isolate and profile PHA producing bacteria from diverse sources such as soil, compost, landfill site, and sewage in Nepal. The initial screening of bacteria was performed by Sudan Black B dye, followed by secondary screening with the more specific Nile Blue A dye to detect PHA accumulation. Out of 343 isolates, 81 were confirmed positive for PHA production which were further processed for PHA extraction. The isolates Ht3d (12.76 ± 1.854%), Nk3e (22.748 ± 3.608%), Mn7d (14.24 ± 2.223%), and Dg5c (14.952 ± 3.401%) from soil, compost, landfill, and sewage respectively, showed the highest PHA accumulation and were biochemically identified as Bacillus circulans , Bacillus subtilis , Staphylococcus aureus , Staphylococcus spp., respectively. The yield ratio for isolate Ht3d significantly increased by 2.74 fold under the optimal conditions (pH 7, 35°C, and 48 h with glucose as carbon source) which was 34.99 ± 5.61% having titer value of 0.82 g/L and production rate of 0.034 g/L/h with respect to 2.4 g/L of cell biomass. The production rate and dry cell weight of other isolates were also enhanced under different optimal conditions. The characterization of the produced biopolymer through UV-Visible spectrophotometry provided maximum absorbance at 232 nm and the FT-IR spectroscopy indicated the presence of O-H and C-H vibrations along with C = O, C-O-C stretching which collectively confirmed the presence of PHA. Polyhydroxyalkanoates Nile Blue A Sudan Black B Bioplastic Plastic pollution Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 1. Introduction Plastics are synthetic organic polymers derived from hydrocarbons of natural gases or crude oils which have become crucial commodity in the modern world due to its versatility, durability and cost-effectiveness [ 8 , 33 ]. The annual usage of non-degradable long lasting material plastic shows continual trend of growth regardless of the environmental scrutiny; thus, being a subject of concern with regards to its impact on the environment [ 9 , 25 , 27 ]. As of 2015, plastic wastes generated was estimated around 6300 million metric tons (Mt), out of which merely 9% was being recycled, 12% incinerated and a staggering 79% accumulating in landfills or natural environments; however, by 2017, the total plastic generation till date was bumped into 9 billion tons from which only 9% of total had been recycled and contributing such large amounts of plastics for environmental contamination [ 9 , 25 ]. In regards to the environmental and health concerns streamlined with waste management practices, there is a growing demand for ecofriendly and cost effective alternatives to mitigate plastic pollution [ 21 ]. Among the alternatives, bio-based plastics like Polyhydroxyalkanoates (PHA) shows promising potential and are bio-polyesters stored within microorganisms as carbon or energy reserves under nutrition limited conditions [ 10 , 13 , 31 ]. Notably, PHA possesses key characteristics of being environmentally friendly, biocompatibility and complete biodegradability into carbon dioxide and water within a year [ 5 ]. These attribute of green plastic PHA provides positive environmental impact without contributing to landfill persistence as compared to conventional plastic. Moreover, due to its compatibility, PHA shows extensive application across industries, particularly in the biomedical field for tissue engineering, bio-implant patches, drug delivery, and wound dressing; in food industry for packaging and disposable products; in agricultural sector for crop protection and biodegradable carriers; and in other sectors as automobile components, ultracapacitors and disposable clothes. These inherent qualities of PHA render them as viable substitute of conventional plastics [ 1 , 31 ]. PHA are easily biodegradable in diverse environments, including soil, freshwater, marine systems, and are compostable at both home and industrial level [ 16 ]. The distinct advantage of PHA lies in its diverse synthesis pathway as it can be produced from substrates such as soluble sources of organic carbon, solid waste products or industrial waste gases rich in C1 compounds such as carbon dioxide, methane and methanol [ 2 , 30 , 41 ]. In the microbial community, diverse groups of microorganisms commonly including autotrophs, methanotrophs, and acetogens synthesize PHA, by conversion of renewable carbon rich resources [ 16 , 30 ]. The most recurrent producer of PHA includes Arthrobacter spp., Bacillus spp., Halomonas spp., Paracoccus spp., Rhodobaca spp., Exiguobacterium spp., Pseudomonas spp., Brevibacterium spp., and Achromobacter spp. [ 24 , 39 ]. To mitigate the impact of plastics, extensive research has been conducted using advanced biotechnological processes to produce biodegradable plastics, such as PHAs from microorganisms, that replicate properties of conventional plastics. This study emphasizes to isolate and screen bacterial strains capable of producing PHA from diverse environmental sources in Nepal and to analyze and optimize the yield of selected high performing isolated under varying cultural conditions. The few research studies in Nepal on this topic highlight the significance of this study, as it provides insights into distribution and potential of these organisms for producing PHA. 2. Materials and Methods 2.1 Sample size and sample site About 100 g of 20 samples each were collected from 4 different environmental settings which included soil, compost, landfill site soil, and sewage sediments. Five different sites for each sample were randomly chosen for the sample collection, which are listed in the Supplementary File, Section A. 2.2 Sample collection and processing for isolation of bacteria Each type of samples was collected aseptically in sterile plastic zip-lock bags from different places and were stored at room temperature until analysis [ 13 , 37 ]. 5 g of sample was thoroughly agitated with the help of vortex mixer in 45 ml of sterile distilled water. The suspension was serially diluted from 10 − 1 to 10 − 7 . For isolation of organism, spread plate method was followed where 0.1 ml of selected dilution was dispensed and spread over Nutrient Agar surface using sterile bent glass rod which was incubated at 37°C for 24 h. After incubation morphologically different colonies were selected for subculture for further screening process [ 26 ]. 2.3 Primary screening with Sudan Black B The sub-cultured isolates were streaked on carbon-enriched agar medium consisting of 6.0g of Na 2 HPO 4 , 3.0g KH 2 PO 4 , 1.0g NH 4 Cl, 0.05g yeast extract, 0.5g NaCl, 17g agar-agar, and 10g glucose per liter solution. The pH of the medium was adjusted to 7.0 and after streaking the plates were incubated for 24h at 37°C. After incubation, the primary screening for the PHA producing bacterial colonies was performed by pouring 0.02% alcoholic solution of SBB on the plates which were left undisturbed for 20 minutes. The excess dye was carefully decanted without disturbing the colonies and the plates were rinsed by addition of absolute ethanol. The colonies positive for PHA production appeared bluish black by incorporation of SBB while colonies negative for PHA appeared white [ 38 ]. 2.4 Secondary screening for PHA production The selected positive strains after primary screening were qualitatively screened, in duplicate, using PHA detecting agar (PDA) containing Nile Blue A (NBA) stain which has the following composition: 4g Nutrient Broth, 10g Nutrient Agar, and 0.25mg NBA for 500 ml solution. The streaked plates after incubation at 37°C for 24h were illuminated under UV light at 312 nm using UV Transilluminator, where the presence of PHA accumulation was indicated by bright orange fluorescence. The strains with orange fluorescence were selected for further processing [ 13 ]. 2.5 Identification of selected isolates The selected strains with ability to produce PHA were characterized by using morphological and biochemical examinations. The morphological character of bacterial isolates along with Gram reaction test were determined for performing various biochemical tests such as catalase, oxidase, citrate utilization, indole production test, urease activity, and carbohydrate utilization tests [ 24 ]. 2.6 Inoculum preparation The inoculum preparation was performed using 10 ml sterile Nutrient broth where a loopful of pure culture was inoculated and then incubated overnight at 37°C at 120 rpm shaking speed in shaker incubator. This liquid culture was used as inoculum or seed culture for further study [ 38 ]. 2.7 Submerged fermentation for PHA production The selected strains were subjected to submerged fermentation using Mineral Salt Medium (MSM) containing (g/L): 40g glucose, 1.0g urea, 0.52g MgSO 4 , 0.02g CaCl 2 , 4.0g Na 2 HPO 4 , 0.16g yeast extract and 0.1 ml of trace element solution. The trace element solution was prepared by incorporating 5g of FeSO 4 .7H 2 O, 1.1245g of ZnSO 4 .7H 2 O, 0.5g of CuSO 4 .5H 2 O, 0.25g of MnSO 4 .5H 2 O, 1g of CaCl 2 .2H 2 O, 0.115g of Na 2 B 4 O 7 .10H 2 O, and 0.05g of (NH 3 ) 4 Mo 7 O 24 in 500 ml distilled water [ 13 , 38 ]. 2.8 Extraction of PHA The extraction of PHA was performed using modified gravimetric analysis method. The fermented medium of selected strains was centrifuged at 5000 rpm for 30 minutes to obtain the cell biomass which was performed in triplicate. The biomass was dried at 40–50°C which was weighed and was treated with 6.25 M NaCl solution at 37°C for 1h to recover the PHA. The content was then centrifuged at 5000 rpm for 15 minutes at room temperature and then the pellets were washed three times with distilled water and was again centrifuged at 5000 rpm for 10 minutes. the recovered pellets were then suspended in NaClO (4%, v/v) and chloroform at 1:1 (v/v) ratio. The suspension was incubated at 37°C for 1h and the mixture was centrifuged at 5000 rpm for 30 mins. After centrifugation, three distinct phases were obtained with upper phase of hypochlorite solution, middle phase with non-PHA cell mass and bottom phase of chloroform with PHA. The upper layer was removed by pipetting with the help of micropipette while the middle layer was filtered using Whatman filter paper. The chloroform suspension was then added with hexane (100%) (v/v) for the precipitation of PHA content which was recovered by drying at 40–50°C by removing the traces of chloroform and hexane [ 21 ]. 2.9 Cell weight determination and PHA yield The PHA content recovered was quantified in terms of percentage production (%PHA) in cell dry weight (CDW) which was calculated as ratio between total dry weight of PHA to CDW. The following formulas were applied for the quantification: [ 13 , 26 ] Cell dry weight (CDW) = weight of the falcon tube with dried pellets – weight of the empty falcon tube Dry weight of extracted PHA = weight of falcon tube with dried PHA – weight of empty falcon tube $$\:\text{%}\text{P}\text{H}\text{A}=\:\frac{\text{P}\text{H}\text{A}\:\text{w}\text{e}\text{i}\text{g}\text{h}\text{t}\:\times\:100}{\text{D}\text{r}\text{y}\:\text{w}\text{e}\text{i}\text{g}\text{h}\text{t}\:\text{o}\text{f}\:\text{w}\text{h}\text{o}\text{l}\text{e}\:\text{c}\text{e}\text{l}\text{l}}$$ 2.10 Optimization for PHA production 2.10.1 Effect of carbon source The selected strains for optimization were initially cultured in Nutrient broth medium at 37°C, 120rpm for 24h. Subsequently, it was transferred to 50 ml MSM medium containing 2% w/v concentration of glucose, fructose, sucrose, and maltose as test carbon sources. The physical parameters including temperature (37°C), pH (7), and agitation speed (120 rpm) was maintained constantly throughout the process. After fermentation, the total biomass and PHA production were determined for each substrate in triplicate and the optimal carbon source was determined based on the highest PHA yield achieved [ 38 ]. 2.10.2 Effect of time The optimization for the incubation time of the selected strains was also studied by incubating the strains in fermentation medium with glucose as sole carbon source for 24h, 48h, 72h, 96h, and 120h. The samples were extracted at these time interval in triplicate for determination of PHA yield [ 21 ]. 2.10.3 Effect of pH The effect of pH on the PHA production was also studied using different initial pH values of 5, 6, 7, 8, and 9 of the fermentation medium with glucose as carbon source. The estimation of PHA yield was performed in triplicate after incubation in pH range at 37°C for 72h [ 21 , 38 ]. 2.10.4 Effect of temperature The physical variable incubation temperature was also optimized for the PHA production by incubating the selected strains in the fermentation medium with glucose as carbon source over a range of temperature which were 25°C, 30°C, 35°C, and 40°C. After incubation at this temperature for 72 h, the PHA production was estimated for each temperature in triplicate [ 21 , 38 ]. 2.11 UV-Visible spectrophotometry (Crotonic acid assay) The crude PHA extracted was digested in 10ml of conc. H 2 SO 4 at 100°C (water bath) for 10 minutes. With the use of UV-Visible spectrophotometer, the preliminary identification of the PHA, the digested product was analyzed at 235 nm in the range of 200 to 800 nm; where H 2 SO 4 was used as blank [ 3 ]. 2.12 FTIR analysis of PHA The produced PHA was characterized by using Fourier Transform InfraRed spectroscopy where the obtained peak values were utilized to interpret the presence of specific functional groups in the biopolymer PHA [ 26 ]. 2.13 Preparation of PHA film 50 mg of extracted PHA was dissolved in 1 ml of chloroform in a microfuge tube and the tube was placed in the oven at 50°C for complete vaporization of chloroform. The PHA films was obtained within the microfuge tube as result of evaporation of chloroform [ 22 ]. 2.14 Statistical analysis The experiments were carried out in triplicate and the values were recorded as mean ± standard deviation using Microsoft Excel 2019 [ 26 ] 3. Results and Discussion Environmental samples such as soil, landfill, sewage sediments and compost were selected based on their variable traits as these sample maintain different microbial ecosystem. The samples were collected from different geographical areas of Nepal (Supplementary File, Section A). After processing by standard techniques, on observation of isolated bacterial colonies, 343 colonies with distinct morphological features from were selected for further screening process to determine their ability to produce PHAs. 3.1 Screening of PHA producing isolates A total of 343 bacterial isolates were initially screened for PHA accumulation using Sudan Black B (SBB) staining. Among them, 189 isolates exhibited bluish-black coloration, indicating positive lipid accumulation. In contrast, non-PHA producers retained their original whitish appearance after decolorization with absolute alcohol. The distribution of PHA accumulation isolates varied notably across environmental samples, with the highest abundance observed in sewage samples, followed by landfill, soil, and compost. The compost sample yielded the lowest number of positive isolates, although this did not necessarily correlate with the production efficiency. Geographical variability of PHA positive isolates is detailed in Supplementary File (Section A). Sudan Black B, a thermostable and lipophilic dye, effectively differentiates lipid containing colonies from non-producers, even with limited biomass. Despite variation in the degree of staining among positive colonies, the contrast with pale-stained negative colonies was distinct, validating the dye’s utility in preliminary screening [12]. Subsequent secondary screening using Nile Blue A (NBA) refined the selection to 81 isolates (43% of SBB positive strains), which exhibited bright orange fluorescence under 312 nm UV light and regarded as true PHA producers (Figure 1). This two-step screening approach improved the specificity of isolate selection. This result aligns with previous studies [13], where a similar reduction in potential strains was observed after fluorescent based confirmation. Both SBB and NBA have been reported as reliable indicators for identifying PHA production in bacterial cells [12, 15, 19]. 3.2 Microscopic Characterization On Gram’s staining, 72 isolates out of 81 (100%) were found to be Gram-positive whereas 9 isolates were Gram-negative (Figure 2). The Gram’s reaction of the all the isolates is provided in the Supplementary File, Section B. The number of Gram-positive bacteria dominated the environment microflora as almost 90% of all the isolates were Gram-positive. This result show high degree of similarity with previous study by [17] reporting 56 Gram-positive bacteria with 38 being rods, 18 cocci, and 25 Gram-negative rods from various types of contaminated soil samples. Although there are limitations for literature reporting PHA production among Gram-negative cocci, some researchers have reported Azotobacter spp., showing ability to accumulate PHA [7]. 3.3 Quantitative analysis of PHA production Among 81 strains utilized for fermentation process, PHA yield was quantified for the 66 strains, while the remaining 15 strains did not yield determinable amounts of PHA. Upon analyzing the obtained data, the yield ratio for most isolates were found to be in the lower range while only few isolates produced PHA in higher ratio (Figure 3). The highest distribution of the isolates was observed in the range of 0-5% with 28 isolates while only 1 isolate was found to yield PHA in the range 20-25%. The isolate Nk3e was found to show the highest average yield of 22.748 ± 3.608% while the lowest was demonstrated by the sample Nk3i with yield percentage of 0.273 ± 0.067% by dry cell weight, which were both isolated from compost sample (Table 2). Despite limited literature, a study has reported the isolation of strain Cupriavidus spp., from compost, with ability to produce PHA content of 75.3% of dry cell weight, which was comparably higher than all the compost isolates from this study [42]. Among other samples, the highest yield of PHA was obtained for the isolate Ht3d from soil with 12.76 ± 1.854% (Table 1), Mn7d from landfill with 14.24 ± 2.223% (Table 3), and Dg5c from sewage sample with 14.952 ± 3.401% (Table 4). A study reported the B. thuringiensis strain isolated from the soil with PHA accumulation of 19% by weight of cell biomass, which was similar to the yield rate from soil isolate Ht3d [6]. Moreover, the study by [32] has reported the PHA yield as high as 57% and as low as 11.23% from different bacterial strains isolated from landfill sites, which upon comparison, the isolate in this study was found to have higher correlation with the lower yielding isolate. Similarly, the study by [26] isolated various bacterial strains from sewage sample with ability to yield PHA within the range of 5-30%, which shows relatively significant correlation with the sewage isolate Dg5c. Table 1: Quantification of cell dry weight and PHA yield among Soil isolates Name of Isolate Observed PHA yield % (Avg ± SD) Cell Dry Weight (CDW) (g/L) PHA Yield (g/L) % Yield Ht3d 12.76±1.854 0.31 0.04 12.817 Sm5a 10.991±7.182 0.367 0.036 9.809 Sy3b 7.035±1.456 1.19 0.091 7.689 Sy3a 6.916±3.308 0.657 0.044 6.746 CG1a 6.925±1.727 0.483 0.033 6.724 CG1c 5.944±0.589 0.59 0.035 5.881 Ht3g 5.656±2.296 3.967 0.21 5.286 Ht5a 4.387±1.513 0.893 0.038 4.276 Sm3f 3.466±0.837 0.98 0.034 3.446 CG5a 2.309±0.675 3.02 0.068 2.249 CG3c 2.259±1.891 7.407 0.157 2.121 CG1b 1.132±0.35 4.65 0.053 1.131 *Yield not determined among soil: Sm3e, Ht3a, Ht3b, Ht3c, Ht3f, Ht5f Table 2: Quantification of cell dry weight and PHA yield among Compost isolates Name of Isolate Observed PHA yield % (Avg ± SD) Cell Dry Weight (CDW) (g/L) PHA yield (g/L) % Yield NK3e 22.748±3.608 2.467 0.543 22.014 NK3f 18.866±2.704 1.7 0.318 18.706 Bn6b 18.492±2.33 1.733 0.314 18.135 Bn6a 17.983±3.443 1.8 0.315 17.481 KS3a 13.866±2.263 4.367 0.585 13.405 Bt3c 12.813±3.475 2.267 0.291 12.853 NK3c 8.054±0.647 0.307 0.025 8.033 Bt3b 8.566±1.534 0.62 0.05 8.005 NK3i 4.963±1.227 0.97 0.048 4.948 Bt3l 3.612±1.015 1.579 0.579 3.669 Bt3m 4.177±2.434 0.79 0.028 3.578 Bt3e 3.02±1.288 2.367 0.067 2.852 NK3a 2.154±1.257 1.503 0.031 2.042 Bt3g 1.112±0.607 3.07 0.03 0.976 NK3g 0.273±0.067 0.983 0.026 0.265 *Yield not determined among Compost: Ks3b, Bt3h Table 3: Quantification of cell dry weight and PHA yield among Landfill isolates Name of Isolate Observed PHA yield % (Avg ± SD) Cell Dry Weight (CDW) (g/L) PHA yield (g/L) % Yield Mn7d 14.24±2.223 3.767 0.533 14.15 Mn7c 13.978±3.263 3.967 0.548 13.824 Mn5e 12.572±0.493 3.567 0.447 12.542 Mn7b 11.901+1.002 4 0.478 11.942 Bl3a 11.686±0.631 3.5 0.408 11.667 Mn3e 9.937±1.407 0.52 0.048 9.288 Mn3d 7.903±1.068 0.57 0.044 7.795 Mn3a 6.582±3.308 0.53 0.035 6.541 Mn7a 6.41±0.782 0.69 0.044 6.396 Sb3a 6.257±2.617 3.567 0.203 5.682 Sb3c 2.716±0.161 2.237 0.061 2.717 Sb3j 2.281±0.321 0.413 0.01 2.379 Mn3f 2.181±0.651 0.713 0.015 2.033 Nz7a 1.824±0.58 3.043 0.052 1.705 *Yield not determined among Landfill isolates: Bl3d Table 4: Quantification of cell dry weight and PHA yield among Sewage isolates Name of Isolate Observed PHA yield % (Avg ± SD) Cell Dry Weight (CDW) (g/L) PHA yield (g/L) % Yield Dg5c 14.952±3.401 3.233 0.458 14.17 Dg3d 11.729±1.063 0.34 0.041 11.96 Tk3g 11.988±0.693 0.383 0.045 11.69 Dg3j 9.083±1.583 1.333 0.132 9.875 Kr3p 8.528±3.028 0.32 0.028 8.635 Tk3j 7.381±2.247 0.677 0.047 6.872 Gt5a 6.371±0.387 0.223 0.015 6.582 Dg3l 5.725±4.71 0.363 0.023 6.394 Kr3u 7.278±2.327 0.453 0.028 6.213 Gt5b 5.549±2.179 0.273 0.016 5.744 Dg3a 5.066±1.66 0.497 0.025 5.074 TK3h 5.199±2.289 0.623 0.031 5.032 Kr3x 4.43±1.111 0.407 0.018 4.328 Kr3o 4.392±1.429 0.967 0.04 4.186 Kr3f 4.034±0.478 0.31 0.013 4.097 Gt3b 3.942±1.896 0.44 0.017 3.894 Kr3r 4.356±2.121 0.99 0.038 3.805 Jr3f 3.958±1.782 0.413 0.013 3.169 Dg5b 5.615±4.298 0.51 0.016 3.052 Kr3e 3.312±1.321 1.063 0.03 2.815 Dg3n 2.762±1.012 1.433 0.035 2.456 Dg3k 2.93±1.836 0.177 0.004 2.283 Tk3c 2.571±1.052 1.447 0.03 2.046 Kr3g 1.909±0.467 0.85 0.014 1.625 Kr3m 1.389±0.334 4.3 0.058 1.337 *Yield not determined among Sewage isolates: Kr3a, Kr3d, Jr3a, Jr3h, Jr5c, Jr5e From the results, it can be duly noted that bacteria isolated from compost are capable of higher yields of PHAs as compared to those of soil, sewage and landfill samples. Primarily, these differences in PHA yield are due to the variability in sample sites which mostly involved the divergence in microbial ecology along with additional metabolic variables such as temperature, aeration, and pH. The higher accumulation among compost isolates can also be attributed to several environmental and biological factors which are unique to compost ecosystems, such as high C:N ratio, nutrient rich environment, and thermophilic and aerobic condition [ 4, 35, 36]. 3.4 Morphological and Biochemical characterization From the total of 81 isolates, 4 of the isolates were selected for biochemical profiling determined based on the highest yielding strains from each sample type. The selected strain from soil sample Ht3d was determined to be Bacillus circulans , Nk3e from compost as Bacillus subtilis , Mn7d from landfill as Staphylococcus aureus , while Dg5c from sewage sample was inferred as Staphylococcus spp (Table 5) . which was identified using Bergey’s Manual of Determinative Bacteriology (Supplementary File, Section C). Table 5 : Morphological and Biochemical profiling of selected isolates Isolates Tests Ht3d Nk3e Mn7d Dg5c Gram staining Positive rod Positive rod Positive cocci Positive cocci Catalase + + + + Oxidase - + + - Coagulase * * + - Mannitol fermentation * * + - Pigment * * Golden - Starch hydrolysis + + * * VP - + * * Spore + - * * Cell diameter ≥1µm - + * * Citrate utilization - + * * Growth at 6.5% NaCl - + * * Growth at 55 0 C - - * * Acid from arabinose + - * * Bacillus circulans Bacillus subtilis Staphylococcus aureus Staphylococcus spp. Positive (+), Negative (-), Not determined (*) 3.5 Optimization The selected isolates for each sample with the highest yield were further processed for determining the optimal condition of PHA production. Parameters such as carbon sources, time, pH, and temperature were manipulated at different levels one at a time, for determining their optimal level required for maximum yield of PHA. 3.5.1 Optimization of carbon sources Carbohydrates serve as primary carbon sources for bacterial growth and PHA production, and different sugars can be metabolized at varying efficiencies depending on the bacterial strain and its enzymatic machinery [28]. After fermentation at constant temperature of 37°C, pH 7, and agitation speed of 120 rpm, the cell dry weight and PHA yield for each sample were determined. Each isolate exhibits a distinct preference for specific carbohydrates for maximum PHA production (Table 6). The highest yield of PHA with respect to cell dry weight was observed for the sample Ht3d which yielded 34.99 ± 5.61% of PHA with 2.4 g/L of cell biomass utilizing the glucose carbon source followed by isolate Nk3e with 24.26 ± 9.74% PHA yield and 4.17 g/L cell biomass from same carbon source. The isolate Mn7d was observed to show relatively high PHA yield for the substrate sucrose. Similarly, the sewage isolate Dg5c was observed to have higher affinity towards maltose substrate as compared to other isolates. With context to optimization for carbon substrate, the findings from research by [21] presented different strains of Bacillus spp., to yield maximum PHA from glucose and molasses which were 49.46 ± 2.79% and 45.86 ± 2.17% respectively. Meanwhile, some studies have reported prominent production of polyhydroxyalkanoates from both carbon sources, sucrose and glucose, using different strains of Bacillus spp. upon optimization, which was parallel to this study [20]. Table 6: Determination of cell dry weight and PHA yield after optimization of carbon Carbon Source Isolate Observed PHA yield % (Avg ± SD) Cell Dry Weight (CDW) (g/L) PHA yield (g/L) % Yield Glucose Ht3d 34.99±5.61 2.4 0.823 34.305 Mn7d 10.37±2.54 3.97 0.402 10.134 Nk3e 24.26±9.74 4.17 1.011 24.264 Dg5c 4.03±2.48 0.86 0.037 4.306 Sucrose Ht3d 7.44±1.69 0.67 0.0493 7.4 Mn7d 18.85±3.72 3.1 0.5853 18.88 Nk3e 13.85±0.51 3.7 0.511 13.81 Dg5c 3.88±0.63 1.26 0.0484 3.83 Fructose Ht3d 4.33±1.16 1.28 0.0529 4.146 Mn7d 9.91±2.51 5.17 0.484 9.367 Nk3e 17.97±2.83 4.47 0.7783 17.425 Dg5c 10.88±4.55 5.8 0.5913 10.19 Maltose Ht3d 6.401±2.28 0.75 0.0451 6.04 Mn7d 4.97±0.59 0.96 0.0472 4.92 Nk3e 2.47±0.91 2.28 0.0465 2.036 Dg5c 7.31±4.59 1.07 0.0784 7.35 3.5.2 Optimization of pH Optimal pH conditions are crucial for maximizing PHA yield, as pH affects enzyme activity, nutrient availability, and overall bacterial growth. After fermentation at constant temperature of 37°C, glucose as carbon source, and agitation speed of 120 rpm, the cell dry weight and PHA yield for each sample were determined. Table 7: Determination of cell dry weight and PHA yield after optimization of pH pH Isolate Observed PHA yield % (Avg ± SD) Cell Dry Weight (CDW) (g/L) PHA yield (g/L) % Yield 5 Ht3d 7.902± 1.35 2.53 0.196 7.724 Nk3e 7.48±0.873 4.3 0.321 7.449 Dg5c 8.37±0.37 4.6 0.379 8.25 Mn7d 12.7±1.51 3.1 0.389 12.57 6 Ht3d 15.7±1.68 2.37 0.364 15.37 Nk3e 10.7±2.25 0.76 0.079 10.44 Dg5c 14.7±3.77 2.87 0.409 14.27 Mn7d 7.87±1.61 4.93 0.359 7.28 7 Ht3d 12.7±1.85 3.1 0.397 12.82 Nk3e 21.7±2.64 3.8 0.826 21.73 Dg5c 17.7±2.56 4.37 0.758 17.36 Mn7d 14.7±2.22 3.77 0.533 14.15 8 Ht3d 1.37±0.01 2.59 0.0345 1.33 Nk3e 1.57±0.27 1.74 0.0265 1.52 Dg5c 0.97±0.17 2.2 0.0217 0.98 Mn7d 0.67±0.26 2.65 0.0163 0.615 9 Ht3d 0.47±0.32 2.45 0.011 0.452 Nk3e 1.47±0.19 0.807 0.0117 1.454 Dg5c 0.57±0.42 2.29 0.0112 0.491 Mn7d 0.47±0.09 2.25 0.0103 0.459 The data reveals that the isolates exhibit a distinct preference for slight acidic / neutral pH for maximum PHA production (Table 7). The maximum average PHA yield among the isolates was observed in pH 7, where Nk3e isolate produced highest yield of 21.09 ± 2.64% with 3.8 g/L cell biomass. At pH 5, the isolate Mn7d showed higher affinity for PHA accumulation and cell biomass production at pH 5 rather than pH 7, which was 12.75 ± 1.52% and 3.1 g/L. The yield ratio at alkaline pH 8 and 9 were found to be significantly lower for all isolates as compared to the acidic and neutral pH as the highest yield of 1.55 ± 0.28% and 1.44 ± 0.19% was obtained from isolate Nk3e at pH 8 and 9 respectively. Thus, the optimal production and accumulation of PHAs by bacterial isolates were observed around pH 7. The least of the yield was noted at pH 8 and pH 9 among all the isolates. This drastic reduction in PHA yields at pH 8 and pH 9 for all isolates indicates that alkaline conditions are unfavorable for PHA production. The reduction in PHA yield observed under extreme pH conditions may be attributed to disruptions in intracellular pH homeostasis caused by the external environment. A shift in environmental pH can influence intracellular conditions, potentially leading to enzyme instability, impaired metabolic flux, and redirection of energy towards maintaining pH balance rather than toward biosynthesis. Interestingly, most of the isolates in this study exhibited relatively higher biomass accumulation under acidic conditions compared to alkaline ones, suggesting a degree of acid tolerance. However, higher biomass did not always correlate with higher PHA accumulation, implying that pH may have a differential effect on growth versus PHA biosynthetic pathways. The higher yield of PHA at neutral pH observed in this study shows high correlation with the previous studies by [28] and [13], reporting neutral pH to be favorable for maximum PHA accumulation. Researches have been found to suggest initial alkaline pH (pH 9) for the strain Ensifer sp., to achieve maximum PHA yield directly affecting enzyme activities of PHA producing bacteria [14]. This further provides evidence that different bacterial strains have varying optimal pH levels for PHA production, which depends on the enzymatic integrity and activity at different pH conditions. 3.5.3 Optimization of Temperature Temperature is a crucial factor affecting enzyme activity, cell membrane fluidity, and microbial metabolism, thereby influencing PHA production [40]. Table 8: Determination of cell dry weight and PHA yield after optimization of incubation temperature Temperature (°C) Isolate Observed PHA yield % (Avg ± SD) Cell Dry Weight (CDW) (g/L) PHA yield (g/L) % Yield 25 Ht3d 3.222±0.787 0.933 0.028 3.039 Nk3e 4.890±0.686 0.657 0.029 4.416 Dg5c 3.113±0.726 0.977 0.029 3.020 Mn7d 2.713±0.614 1.073 0.028 2.590 30 Ht3d 20.824±0.940 0.767 0.159 20.783 Nk3e 5.211±0.744 0.623 0.032 5.176 Dg5c 8.114±0.571 5.133 0.409 7.961 Mn7d 20.514±3.022 2.467 0.497 20.162 35 Ht3d 13.123±1.133 1.003 0.131 13.023 Nk3e 21.653±1.829 2.067 0.443 21.452 Dg5c 3.717±1.423 0.853 0.028 3.234 Mn7d 2.259±0.337 1.447 0.032 2.205 40 Ht3d 9.579±1.674 0.277 0.026 9.470 Nk3e 4.319±1.014 0.650 0.027 4.113 Dg5c 10.962±1.413 2.733 0.296 10.841 Mn7d 3.390±0.631 0.793 0.026 3.324 Differences in PHA accumulation across bacterial isolates according to their incubation temperature was evident in this study (Table 8). Lowest incubation temperature of 25°C was found to show lower PHA accumulation as compared to other incubation temperature during optimization. At 30°C, two isolates Ht3d and Mn7d were found to show similar level of PHA yield which were 20.82 ± 0.94% and 20.51 ± 2.47% with the cell biomass 0.77 g/L and 2.47 g/L respectively. The isolate Nk3e preferred the temperature of 35°C for PHA accumulation as it showed highest yield rate of 21.65 ± 1.83% and 2.07 g/L of cell biomass whereas, the higher temperature of 40°C was found to be more suitable for the isolate Dg5c which produced 10.96 ± 1.41% of PHA from 0.79 g/L of cell biomass. For three out of the four isolates (Ht3d, Mn7d and Dg5c), 30°C appears to be a favorable temperature for PHA production. This aligns with the typical temperature preference for mesophilic bacteria, which thrive and exhibit optimal enzyme activity around 30°C. The study by [40], reported the optimal incubation temperature in the range 30–35°C, as the maximum PHA yield of 96.9% was achieved by the strain Paraburkholderia sp. at 35°C, which shows positive correlation with this study as maximum yield was obtained for the sample Nk3e at same temperature. The reduced PHA yields at 25°C and 40°C for most isolates suggest that these temperatures are less optimal for PHA production. This reduction in PHA accumulation with increasing temperature from optimal range have been linked with the decrement of enzymatic activity of microorganisms with increasing temperature [26]. However, Dg5c’s high yield at 40°C indicates its adaptability to higher temperatures. Therefore, maintaining temperatures around 30°C for Ht3d and Mn7d, 35°C for Nk3e and 40°C for Dg5c would be ideal for maximizing PHA production. 3.5.4 Optimization of incubation time Incubation time is a crucial factor affecting bacterial growth phase, nutrient availability, and metabolic activity. All these parameters, affect and influence PHA production. PHAs yield at varying incubation times (24 hours, 48 hours, 72 hours, 96 hours and 120 hours) provides a valuable insight into the temporal dynamics of PHA synthesis. Table 9: Determination of cell dry weight and PHA yield after optimization of incubation time Time (h) Isolate Observed PHA yield % (Avg ± SD) Cell Dry Weight (CDW) (g/L) PHA yield (g/L) % Yield 24 Ht3d 12.69±1.182 2.93 0.38 12.96 Mn7d 26.52±5.36 2.4 0.615 25.625 Nk3e 1.105±0.239 1.26 0.0134 1.059 Dg5c 6.84±1.53 1.23 0.078 6.36 48 Ht3d 27.58±7.25 2.47 0.677 27.46 Mn7d 21.43±2.58 3.6 0.781 21.7 Nk3e 7.63±3.68 5.37 0.383 7.14 Dg5c 7.37±2.47 3.07 0.191 6.23 72 Ht3d 2.37±0.27 5.5 0.128 2.33 Mn7d 15.19±1.48 1.13 0.17 15.029 Nk3e 6.21±1.84 5.57 0.342 6.14 Dg5c 2.88±2.004 7 0.18 2.57 96 Ht3d 2.19±0.79 0.66 0.0134 2.04 Mn7d 4.07±1.57 3.63 0.159 4.38 Nk3e 21.74±2.18 4.93 1.062 21.53 Dg5c 2.156±1.08 1.55 0.0327 2.109 120 Ht3d 0.68±0.312 0.98 0.0072 0.736 Mn7d 0.39±0.29 0.57 0.0021 0.378 Nk3e 3.92±0.796 0.53 0.0209 3.918 Dg5c 1.03±1.17 1.5 0.0191 1.27 Each isolate exhibits a distinct time profile for maximum PHA production, as the PHA yield of all the isolates were found to differ with time (Table 9). The isolate Ht3d, among all isolates, produced highest yield 27.58 ± 7.25% from 2.47 g/L cell biomass at 48 hours which drastically declined in subsequent time intervals. The isolate Nk3e almost gradually increased the PHA yield along the interval with highest yield of 21.74 ± 2.18% and 4.93 g/L cell biomass at the 96 hours. The isolate Mn7d was found to show highest PHA accumulation at 24 hours with yield ratio of 26.52 ± 5.36% and 2.4 g/L cell biomass which decreased gradually over the time interval. At the time interval of 120 hours, the overall production was found to diminish for all the isolates where Nk3e and Dg5c were the only isolate to maintain substantial amount of PHA yield and cell biomass. A study suggested the optimum time for the PHA accumulation in different bacterial strain to be 72 hours, after which there was decline in the production rate [28]. Another study suggested the highest production of PHA in strain of Ensifer sp., was achieved only after longer incubation time of 108 hours, where the bacteria produced 45.54% w/w of PHA from 3.82 g/L of cell dry weight [14]. The incubation time period of 48 hours appears to be the most favorable incubation time for PHA production for isolates Ht3d and Dg5c. This suggests that, PHA synthesis peaked during the late exponential or early stationary phase of growth considering these isolates. Similarly, the extended incubation times i.e., 96 hours and 120 hours, generally resulted in lower PHA yields for most isolates, except for Nk3e at 96 hours. This trend indicates that prolonged incubation may lead to nutrient depletion, accumulation of toxic metabolites or onset of cellular death, all of which, negatively impacts the PHA production. Therefore, maintaining incubation times around 48 hours for Ht3d and Dg5c, 96 hours for Nk3d and 24 hours for Mn7d would be ideal for maximizing the PHA production. 3.6 UV-Vis spectroscopy The crude PHA obtained from different isolates were further processed for the production of Crotonic acid by treatment with concentrated Sulphuric acid at 100°C for 10 mins. The extracted sample was used for the preliminary identification of PHAs using UV-Visible spectroscopy, within a range of 200 to 800 nm, with concentrated sulfuric acid as the standard. Upon analyzing the absorbance value, an absorption maxima at 232.0 nm with an absorbance of 3.793 was noted (Figure 4). Literature has suggested the use of Crotonic acid for the qualitative identification or quantification of the PHA molecule through the utilization of its inherent absorbance characteristics, which show characteristic peak at 235 nm under standard condition [28, 38]. The characteristic peak obtained in this study at 232 nm shows similarity with the peak of standard Crotonic acid at 235 nm [34]. Similarly, another study reported the highest maxima at 235 nm and the absorbance around 3.0 which was similar to the value obtained in this study [20]. 3.7 FT-IR analysis The analysis was carried out over the spectral range of 4000 – 400 cm -1 for the determination of the functional group present on the extracted polymer (Figure 5). The FT-IR results were found to demonstrate transmittance peaks over a range of wavenumber, notably 3437 cm -1 , 2931 cm -1 , 1724 cm -1 , 1379 cm -1 , and 1290 cm - 1 . The peaks observed on the FT-IR spectra for the PHA molecules were identified to have various functional group such as hydroxyl group (O-H) represented by 3437.15 cm -1 , C-H stretching by peak 2932 cm -1 , presence of symmetrical CH3 by 2850.79 cm -1 , ester group (C=O) at 1724.36 cm -1 , followed by stretching groups of -CH2, terminal -CH3, C-O-C, and C-CH3 at 1462.04, 1379.1, 1228.6, and 1060.8 cm -1 respectively, which were cross referenced with various studies (Table 10). Moreover, multiple absorption peaks were observed between 1060 – 600 cm -1 region which was significantly similar to the report by [29], where such bands were observed between 1054.31 to 677.46 cm -1 which were referred as C-O and C-C stretching in amorphous phase. A study has reported the FT-IR analysis of transmittance spectra of PHA with several peaks in the regions 3440 cm -1 for -OH group, 2930 – 2980 cm -1 for C-H stretching of methyl (-CH3), and methylene (-CH2) group, and the region 1380 – 970 cm -1 attributed to C-C, C-H, and C-O group which upon comparison was found to be similar with spectra of the PHA analyzed in this study [14]. Table 10: Characterization of FT-IR peaks for extracted PHA Wavenumber cm -1 Current Study Previous Study Functional Group Reference 3437.15 3438 O-H [29] 2931.8 2932 C-H [18] 2850.79 2852.67 Symmetrical CH3 [29] 1724.36 1724 C=O [11] 1462.04 1453 -CH2 [11] 1379.1 1378.69 -CH3 (terminal) [29] 1228.6 1223.01 C-O-C stretching [26] 1060.8 1058.96 C-CH3 [26] 3.8 PHA film preparation A thin sheet like structure around the walls of the tube was obtained after the evaporation of chloroform, which upon analysis showed highly brittle and fragile nature. This nature of obtained biofilm also correlates with multiple literature studies [13, 22]. 4. Limitations of the study The PHA producing isolates were identified solely based on phenotypic and biochemical tests which cannot provide definitive taxonomic resolution. The use of generalized viable plate method might have excluded strains requiring specific conditions for PHA accumulation. Due to limited resources, polymer purification, detailed chemical characterization, and biodegradability assessments of the extracted PHA were not performed. Furthermore, optimization using alternative substrates such as agro-waste and broader extrinsic parameters and their comparison was limited by the project timeline. 5. Conclusion Despite the variability in sample sources – soil, compost, landfill, and sewage – all environmental habitats yielded bacterial isolates capable of PHA production. Interestingly, compost yielded the fewest positive isolates but produced the highest-yielding strain (Nk3e), highlighting that sample type may not directly predict yield capacity. The top-performing isolates – Bacillus circulans (Ht3d), Bacillus subtilis (Nk3e), Staphylococcus aureus (Mn7d), and Staphylococcus spp. (Dg5c) – achieved maximum yields of 34.99% and 24.26% under optimized conditions. While these yields are promising for the environmental isolates, they remain below industrial benchmarks, which often exceed 50–80% of dry cell weight using high efficiency strains such as Cupriavidus necator under fed-batch or bioreactor conditions. Nonetheless, the significance of this study lies in identifying native PHA producing bacteria from underexplored ecological niches of Nepal – highlighting untapped biodiversity. Further work incorporating molecular identification, cost-effective scale-up strategies, and genetic or metabolic engineering could enhance both yield and feasibility for industrial application. The extracted biopolymer was successfully possessed into film and confirmed via UV-Vis and FT-IR analyses. These findings offer a foundational step toward sustainable bioplastic production using locally sourced strains, aligning with global efforts in circular bioeconomy and plastics alternative. Abbreviations PHA Polyhydroxyalkanoate SBB Sudan Black B NBA Nile Blue A FT-IR Fourier Transform - Infrared UV- Vis Ultra Violet – Visible Mt Million metric tons Declarations Ethics approval and consent to participate Not applicable. Consent for publication Not applicable. Availability of data and materials The authors confirm that the data supporting the findings of the study are available within the article and the supplementary files and can be contacted to the corresponding author. Competing interests The authors declare no competing interests. Funding This research was self-funded by the authors and no external funding was provided. Author’s Contribution SA, SB, RS, and SSS, conceptualized the study; carried out the investigation, data acquisition, and interpretation of data. SA designed the work. SA, and SB collected essential resources and utilized software for visualization and interpretation; and also wrote the manuscript. UK supervised, and validated the study, and reviewed the manuscript. All the authors read and approved the final manuscript. Acknowledgements The authors would like to express sincere gratitude to the Department of Microbiology and St. Xavier’s College for the provision of laboratory facilities during the study period. The authors are deeply indebted towards Mr. Sandesh Maharjan and Mr. Prakash Manandhar (Lecturer, St. Xavier’s College) for their valuable technical assistance during spectroscopy and centrifugation process. The authors are also grateful to the Nepal Academy of Science and Technology (NAST) for providing the FT-IR Spectroscopy required for the study. References Acharjee, S. A., Bharali, P., Gogoi, B., Sorhie, V., Walling, B., Alemtoshi., 2022. PHA-based bioplastic: a potential alternative to address microplastic pollution. Water Air Soil Pollut., 234(1), 1–31. https://doi.org/10.1007/S11270-022-06029-2 Álvarez-Chávez, C. R., Edwards, S., Moure-Eraso, R., Geiser, K., 2012. Sustainability of bio-based plastics: general comparative analysis and recommendations for improvement. J. Clean. Prod., 23(1), 47–56. https://doi.org/10.1016/j.jclepro.2011.10.003 Aragosa, A., Specchia, V., & Frigione, M., 2023. Valorization of waste from argan seeds for polyhydroxybutyrate production using bacterial strains isolated from argan soils. Polymers, 15(8), 1972. https://doi.org/10.3390/polym15081972 Azim, K., Soudi, B., Boukhari, S., Perissol, C., Roussos, S., Thami Alami, I., 2018. Composting parameters and compost quality: a literature review. Org. Agr., 8(2). https://doi.org/10.1007/s13165-017-0180-z Bhuwal, A. K., Singh, G., Aggarwal, N. K., Goyal, V., Yadav, A., 2013. Isolation and screening of polyhydroxyalkanoates producing bacteria from pulp, paper, and cardboard industry wastes. Int. J. Biomater., 2013. https://doi.org/10.1155/2013/752821 Cueva-Almendras, L. C., Alvarado, J. C. A., Fuentes-Olivera, A. J., Llontop-Bernabé, K. S., Cerna, C. E. Q., Rodriguez-Soto, J. C., Cruz-Monzón, J. A., Quezada Alvarez, M. A., 2022. Production of polyhydroxyalkanoate by Bacillus thuringiensis isolated from agricultural soils of Cascas-Peru. Braz. Arch. Biol. Technol., 65. https://doi.org/10.1590/1678-4324-2022220107 El-Nahrawy, S., Abd El-Kodoos, R. Y., Belal, E.-S. B., El-Shouny, W., 2018. Production of poly-β-hydroxybutyrate (PHB) by Azospirillum and Rhizobium sp. EBSS, 2(2018), 1–25. https://doi.org/10.21608/jenvbs.2019.6781.1044 Gaur, V. K., Nguyen-Vo, T. P., Islam, T., Bassey, B. F., Kim, M., Ainala, S. K., Shin, K., & Park, S. (2024). Efficient bioproduction of poly(3-hydroxypropionate) homopolymer using engineered Escherichia coli strains. Bioresource Technology, 397, 130469. https://doi.org/10.1016/j.biortech.2024.130469 Geyer, R., Jambeck, J. R., Law, K. L., 2017. Production, use, and fate of all plastics ever made. Sci. Adv., 3(7). https://doi.org/10.1126/sciadv.1700782 Gill, M. (2014). Bioplastic: a better alternative to plastics. Int. J. Res Appl. Nat. Soc. Sci., 2(8), 113–118. Hamdy, S. M., Danial, A. W., Gad El-Rab, S. M. F., Shoreit, A. A. M., Hesham, A. E.-L., 2022. Production and optimization of bioplastic (Polyhydroxybutyrate) from Bacillus cereus strain SH-02 using response surface methodology. BMC Microbiol., 22(1), 183. https://doi.org/10.1186/s12866-022-02593-z Homolak, J., Joja, M., Markovic, P., Salkovic-Petrisic, M., 2022. Sudan black lipid blot – a rapid and simple method for quantification of lipids in biological samples. BioRxiv. https://doi.org/https://doi.org/10.1101/2022.07.27.501748 Javaid, H., Nawaz, A., Riaz, N., Mukhtar, H., Ikram-Ul-haq, Shah, K. A., Khan, H., Naqvi, S. M., Shakoor, S., Rasool, A., Ullah, K., Manzoor, R., Kaleem, I., Murtaza, G., 2020. Biosynthesis of polyhydroxyalkanoates (PHAs) by the valorization of biomass and synthetic waste. Molecules, 25(23). https://doi.org/10.3390/molecules25235539 Khamkong, T., Penkhrue, W., Lumyong, S., 2022. Optimization of production of polyhydroxyalkanoates (PHAs) from newly isolated Ensifer sp. strain HD34 by response surface methodology. Processes, 10(8). https://doi.org/10.3390/pr10081632 Kitamura, S., Doi, Y., 1994. Staining method of poly(3-hydroxyalkanoic acids) producing bacteria by nile blue. Biotechnol. Tech., 8(5). https://doi.org/10.1007/BF02428979 Koller, M. (2020). Advances in polyhydroxyalkanoate (PHA) production, Volume 2. Bioeng., 7(1). https://doi.org/10.3390/bioengineering7010024 Mascarenhas, J., Aruna, K., 2017. Screening of polyhydroxyalkonates (PHA) accumulating bacteria from diverse habitats. J. Glob. Biosci., 6(3), 4835–4848. http://www.mutagens.co.in/jgb/vol.06/3/060304.pdf Mazwan, M., Febriani, F., Nazaruddin, N., 2023. Isolation and characterization of polyhydroxyalkanoate (PHA) producing bacteria isolate from landfill land of Kampung Jawa Banda Aceh. J. Nat., 23(1), 53–61. https://doi.org/10.24815/jn.v23i1.29746 Mesquita, D. P., Amaral, A. L., Leal, C., Oehmen, A., Reis, M. A. M., Ferreira, E. C., 2015. Polyhydroxyalkanoate granules quantification in mixed microbial cultures using image analysis: sudan black b versus nile blue a staining. Anal. Chim. Acta, 865(1). https://doi.org/10.1016/j.aca.2015.01.018 Mhatre, K. J., Naik, V. A., 2022. Study of bacterial biopolymer production by Bacillus species. Int. J. Curr. Microbiol. Appl. Sci., 11(4), 21–29. https://doi.org/10.20546/ijcmas.2022.1104.004 Mohammed, S., Panda, A. N., Ray, L., 2019. An investigation for recovery of polyhydroxyalkanoates (PHA) from Bacillus sp. BPPI-14 and Bacillus sp. BPPI-19 isolated from plastic waste landfill. Int. J. Biol. Macromol., 134, 1085–1096. https://doi.org/10.1016/j.ijbiomac.2019.05.155 Mohammed, S., Ray, L., 2022. Polyhydroxyalkanoate recovery from newly screened Bacillus sp. LPPI-18 using various methods of extraction from Loktak Lake sediment sample. J. Genet. Eng. Biotechnol., 20(1), 115. https://doi.org/10.1186/S43141-022-00392-7 Moshood, T. D., Nawanir, G., Mahmud, F., Mohamad, F., Ahmad, M. H., AbdulGhani, A., 2022. Sustainability of biodegradable plastics: new problem or solution to solve the global plastic pollution? Curr. Res. Green Sustain. Chem., 5, 100273. https://doi.org/10.1016/J.CRGSC.2022.100273 Muigano, M. N., Anami, S. E., Onguso, J. M., Omare, G. M., 2023. The isolation, screening, and characterization of polyhydroxyalkanoate-producing bacteria from hypersaline lakes in Kenya. Bacteria, 2(2), 81–97. https://doi.org/10.3390/BACTERIA2020007/S1 Nikiema, J., Asiedu, Z., 2022. A review of the cost and effectiveness of solutions to address plastic pollution. Environ. Sci. Pollut. Res., 29(17), 24547–24573. https://doi.org/10.1007/S11356-021-18038-5/TABLES/13 Odeniyi, O. A., Adeola, O. J., 2017. Production and characterization of polyhydroxyalkanoic acid from Bacillus thuringiensis using different carbon substrates. Int. J. Biol. Macromol., 104, 407–413. https://doi.org/10.1016/j.ijbiomac.2017.06.041 Pandey, P., Dhiman, M., Kansal, A., & Subudhi, S. P. (2023). Plastic waste management for sustainable environment: techniques and approaches. Waste Dispos. Sustain. Energy, 5(2). https://doi.org/10.1007/s42768-023-00134-6 Patil, T. D., Ghosh, S., Agarwal, A., Patel, S. K. S., Tripathi, A. D., Mahato, D. K., Kumar, P., Slama, P., Pavlik, A., Haque, S., 2024. Production, optimization, scale up and characterization of polyhydoxyalkanoates copolymers utilizing dairy processing waste. Sci. Rep., 14(1), 1620. https://doi.org/10.1038/s41598-024-52098-0 Rakkan, T., Chana, N., Sangkharak, K., 2022. The integration of textile wastewater treatment with polyhydroxyalkanoate production using newly isolated Enterobacter strain TS3. Waste Biomass Valorization, 13(1), 571–582. https://doi.org/10.1007/s12649-021-01504-z Ray, S., Jin, J. O., Choi, I., Kim, M., 2022. Recent trends of biotechnological production of polyhydroxyalkanoates from C1 carbon sources. Front. Bioeng. Biotechnol., 10. https://doi.org/10.3389/FBIOE.2022.907500 Raza, Z. A., Abid, S., Banat, I. M., 2018. Polyhydroxyalkanoates: characteristics, production, recent developments and applications. Int. Biodeterior. Biodegradation, 126, 45–56. https://doi.org/10.1016/J.IBIOD.2017.10.001 Razak, W. W. A., Mohamad Yusuf, N., Abdul-Aziz, A., Navaratnam, S. K., Zubir, I., Rizlan Ross, E. E., 2019. Screening and isolation of polyhydroxyalkanoates (PHA)-producing bacteria from landfill by using cocoa pod husks as carbon source. Int. J. Eng. Technol., 7(4.14), 51-56. https://doi.org/10.14419/ijet.v7i4.14.27470 Rhodes, C. J. (2018). Plastic pollution and potential solutions. Sci. Prog., 101(3), 207–260. https://doi.org/10.3184/003685018X15294876706211 Salgaonkar, B., Bragança, J., 2017. Utilization of sugarcane bagasse by Halogeometricum borinquense strain E3 for biosynthesis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate). Bioeng., 4(2), 50. https://doi.org/10.3390/bioengineering4020050 Sánchez, Ó. J., Ospina, D. A., Montoya, S., 2017. Compost supplementation with nutrients and microorganisms in composting process. J. Waste Manag., 69. https://doi.org/10.1016/j.wasman.2017.08.012 Sánchez Valencia, A. I., Rojas Zamora, U., Meraz Rodríguez, M., Álvarez Ramírez, J., Salazar Peláez, M. L., Fajardo Ortiz, C., 2021. Effect of C/N ratio on the PHA accumulation capability of microbial mixed culture fed with leachates from the organic fraction of municipal solid waste (OFMSW). JWPE, 40. https://doi.org/10.1016/j.jwpe.2021.101975 Sathianachiyar, S., Devaraj, A., 2013. Biopolymer production by bacterial species using glycerol, a byproduct of biodiesel. Int. J. Sci. Res. Publ., 3(8). Shah, S., Kumar, A., 2021. Production and characterization of polyhydroxyalkanoates from industrial waste using soil bacterial isolates. Braz. J. Microbiol., 52(2), 715–726. https://doi.org/10.1007/s42770-021-00452-z Singh, P., Mahato, R. P., 2019. Screening of potential soil bacteria for detection of polyhydroxyalkanoate (PHA) accumulation. Int. J. Res. Advent Technol., 7(3). Sriyapai, T., Chuarung, T., Kimbara, K., Samosorn, S., Sriyapai, P., 2022. Production and optimization of polyhydroxyalkanoates (PHAs) from Paraburkholderia sp. PFN 29 under submerged fermentation. Electron. J. Biotechnol., 56. https://doi.org/10.1016/j.ejbt.2021.12.003 Vermeer, C. M., Bons, L. J., Kleerebezem, R., 2022. Production of a newly discovered PHA family member with an isobutyrate-fed enrichment culture. Appl. Microbiol. Biotechnol., 106(2), 605. https://doi.org/10.1007/S00253-021-11742-9 Yootoum, A., Jantanasakulwong, K., Rachtanapun, P., Moukamnerd, C., Chaiyaso, T., Pumas, C., Tanadchangsaeng, N., Watanabe, M., Fukui, T., Insomphun, C., 2023. Characterization of newly isolated thermotolerant bacterium Cupriavidus sp. CB15 from composting and its ability to produce polyhydroxyalkanoate from glycerol. Microb. Cell Fact., 22(1). https://doi.org/10.1186/s12934-023-02059-5 Additional Declarations No competing interests reported. Supplementary Files SupplementaryFile.docx PHAgraphs.docx Cite Share Download PDF Status: Published Journal Publication published 25 Aug, 2025 Read the published version in BMC Microbiology → Version 1 posted Editorial decision: Accepted 11 Aug, 2025 Submission checks completed at journal 06 Aug, 2025 First submitted to journal 04 Aug, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5641446","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":495508005,"identity":"b4dc6b6b-6a14-4d7e-8939-8b799a6d8cc8","order_by":0,"name":"Sandesh Adhikari","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6klEQVRIiWNgGAWjYJACCQaGAwwMN9gPPgByePhI0MKTbADSwkaCFgYzCRCPoBb59rMHb3z4c0ee73ZDWuXXHDsZNgbmh49u4NFicCYv2XJm2zPDmXcOHrstuy0Z6DA2Y+McfFoYcsykeRsOM264kZB2W3IbM1ALD5s0Pi3y/W/MpP/8OWwP1GJWLLmtnrAWhhtAWxjYDieCtDB+3HaYsBaDG2+MLXvbDifPvJGTLM247TgPGzMBv8j35xje+PHnsG3fjfSDH39uq7bnZ29++Bivw5ABMw+YJFY5CDD+IEX1KBgFo2AUjBgAAGvFTx1jEy2GAAAAAElFTkSuQmCC","orcid":"","institution":"St. Xavier’s College","correspondingAuthor":true,"prefix":"","firstName":"Sandesh","middleName":"","lastName":"Adhikari","suffix":""},{"id":495508006,"identity":"648eb8c5-b940-4ccb-b1a8-32d3e8a3ce60","order_by":1,"name":"Saman Bhattarai","email":"","orcid":"","institution":"St. Xavier’s College","correspondingAuthor":false,"prefix":"","firstName":"Saman","middleName":"","lastName":"Bhattarai","suffix":""},{"id":495508007,"identity":"005d042e-ae0e-4621-97da-d1b02e6b29ba","order_by":2,"name":"Roja Shrestha","email":"","orcid":"","institution":"St. Xavier’s College","correspondingAuthor":false,"prefix":"","firstName":"Roja","middleName":"","lastName":"Shrestha","suffix":""},{"id":495508008,"identity":"de41f901-50ca-4203-9307-ff5a9192666c","order_by":3,"name":"Shikha Shree Shah","email":"","orcid":"","institution":"St. Xavier’s College","correspondingAuthor":false,"prefix":"","firstName":"Shikha","middleName":"Shree","lastName":"Shah","suffix":""},{"id":495508009,"identity":"20915a50-429a-4165-8a3d-a885adf71895","order_by":4,"name":"Usha Kunwar","email":"","orcid":"","institution":"St. Xavier’s College","correspondingAuthor":false,"prefix":"","firstName":"Usha","middleName":"","lastName":"Kunwar","suffix":""}],"badges":[],"createdAt":"2024-12-14 04:38:05","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5641446/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5641446/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12866-025-04314-8","type":"published","date":"2025-08-25T15:57:25+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":88394169,"identity":"6c0b16f3-f28c-4678-9c4f-57162af95435","added_by":"auto","created_at":"2025-08-06 05:39:16","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":27277,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of screened isolates according to their sample type\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-5641446/v1/5250321a4395e5d73c94fbc3.png"},{"id":88393852,"identity":"363b3bde-5d34-44f1-a4be-f7bdced11543","added_by":"auto","created_at":"2025-08-06 05:31:16","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":41197,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of the PHA producing isolates\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-5641446/v1/29b97041357ce8549a5cca7d.png"},{"id":88393855,"identity":"bd8f8b41-be37-4724-b362-c04f1920aca5","added_by":"auto","created_at":"2025-08-06 05:31:16","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":40367,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of isolates based on the PHA yield percentage\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-5641446/v1/52f48c3eb8ec51744b01ff0b.png"},{"id":88393862,"identity":"1a4a4bc0-ad6b-4356-a89b-db09db64b1d4","added_by":"auto","created_at":"2025-08-06 05:31:16","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":139426,"visible":true,"origin":"","legend":"\u003cp\u003eUV-Vis spectroscopy data of extracted PHA converted into Crotonic acid for analysis\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-5641446/v1/8d679d9eb422b5e8ca4b9940.png"},{"id":88393859,"identity":"b85c2ca7-1304-418f-984f-bf27a378c6b7","added_by":"auto","created_at":"2025-08-06 05:31:16","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":68961,"visible":true,"origin":"","legend":"\u003cp\u003eFT-IR absorption spectra of extracted PHA\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-5641446/v1/8eedee4ff9071eb1d107f934.png"},{"id":90344872,"identity":"52fe6d78-b538-475c-8608-5d5f994ed426","added_by":"auto","created_at":"2025-09-01 16:06:59","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2242425,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5641446/v1/8b1427ab-e48c-4507-a117-5e28f959bdc6.pdf"},{"id":88393853,"identity":"fb59d192-7c9c-45e1-a491-d09f44da16e6","added_by":"auto","created_at":"2025-08-06 05:31:16","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":349476,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryFile.docx","url":"https://assets-eu.researchsquare.com/files/rs-5641446/v1/5b5f5f7f7a020bcded1e81fc.docx"},{"id":88394172,"identity":"1f707ae5-f849-4bc4-9bf4-c69ef5ac07ca","added_by":"auto","created_at":"2025-08-06 05:39:16","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":5330058,"visible":true,"origin":"","legend":"","description":"","filename":"PHAgraphs.docx","url":"https://assets-eu.researchsquare.com/files/rs-5641446/v1/17db2dacdf31d13e013aae90.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Analysis and optimization of Polyhydroxyalkanoates production by environmental bacterial isolates from Nepal","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003ePlastics are synthetic organic polymers derived from hydrocarbons of natural gases or crude oils which have become crucial commodity in the modern world due to its versatility, durability and cost-effectiveness [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. The annual usage of non-degradable long lasting material plastic shows continual trend of growth regardless of the environmental scrutiny; thus, being a subject of concern with regards to its impact on the environment [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. As of 2015, plastic wastes generated was estimated around 6300\u0026nbsp;million metric tons (Mt), out of which merely 9% was being recycled, 12% incinerated and a staggering 79% accumulating in landfills or natural environments; however, by 2017, the total plastic generation till date was bumped into 9\u0026nbsp;billion tons from which only 9% of total had been recycled and contributing such large amounts of plastics for environmental contamination [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn regards to the environmental and health concerns streamlined with waste management practices, there is a growing demand for ecofriendly and cost effective alternatives to mitigate plastic pollution [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Among the alternatives, bio-based plastics like Polyhydroxyalkanoates (PHA) shows promising potential and are bio-polyesters stored within microorganisms as carbon or energy reserves under nutrition limited conditions [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. Notably, PHA possesses key characteristics of being environmentally friendly, biocompatibility and complete biodegradability into carbon dioxide and water within a year [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. These attribute of green plastic PHA provides positive environmental impact without contributing to landfill persistence as compared to conventional plastic. Moreover, due to its compatibility, PHA shows extensive application across industries, particularly in the biomedical field for tissue engineering, bio-implant patches, drug delivery, and wound dressing; in food industry for packaging and disposable products; in agricultural sector for crop protection and biodegradable carriers; and in other sectors as automobile components, ultracapacitors and disposable clothes. These inherent qualities of PHA render them as viable substitute of conventional plastics [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e].\u003c/p\u003e\u003cp\u003ePHA are easily biodegradable in diverse environments, including soil, freshwater, marine systems, and are compostable at both home and industrial level [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. The distinct advantage of PHA lies in its diverse synthesis pathway as it can be produced from substrates such as soluble sources of organic carbon, solid waste products or industrial waste gases rich in C1 compounds such as carbon dioxide, methane and methanol [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]. In the microbial community, diverse groups of microorganisms commonly including autotrophs, methanotrophs, and acetogens synthesize PHA, by conversion of renewable carbon rich resources [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. The most recurrent producer of PHA includes \u003cem\u003eArthrobacter\u003c/em\u003e spp., \u003cem\u003eBacillus\u003c/em\u003e spp., \u003cem\u003eHalomonas\u003c/em\u003e spp., \u003cem\u003eParacoccus\u003c/em\u003e spp., \u003cem\u003eRhodobaca\u003c/em\u003e spp., \u003cem\u003eExiguobacterium\u003c/em\u003e spp., \u003cem\u003ePseudomonas\u003c/em\u003e spp., \u003cem\u003eBrevibacterium\u003c/em\u003e spp., and \u003cem\u003eAchromobacter\u003c/em\u003e spp. [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eTo mitigate the impact of plastics, extensive research has been conducted using advanced biotechnological processes to produce biodegradable plastics, such as PHAs from microorganisms, that replicate properties of conventional plastics. This study emphasizes to isolate and screen bacterial strains capable of producing PHA from diverse environmental sources in Nepal and to analyze and optimize the yield of selected high performing isolated under varying cultural conditions. The few research studies in Nepal on this topic highlight the significance of this study, as it provides insights into distribution and potential of these organisms for producing PHA.\u003c/p\u003e"},{"header":"2. Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n \u003ch2\u003e2.1 Sample size and sample site\u003c/h2\u003e\n \u003cp\u003eAbout 100 g of 20 samples each were collected from 4 different environmental settings which included soil, compost, landfill site soil, and sewage sediments. Five different sites for each sample were randomly chosen for the sample collection, which are listed in the Supplementary File, Section A.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\n \u003ch2\u003e2.2 Sample collection and processing for isolation of bacteria\u003c/h2\u003e\n \u003cp\u003eEach type of samples was collected aseptically in sterile plastic zip-lock bags from different places and were stored at room temperature until analysis [\u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e37\u003c/span\u003e]. 5 g of sample was thoroughly agitated with the help of vortex mixer in 45 ml of sterile distilled water. The suspension was serially diluted from 10\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e to 10\u003csup\u003e\u0026minus;\u0026thinsp;7\u003c/sup\u003e. For isolation of organism, spread plate method was followed where 0.1 ml of selected dilution was dispensed and spread over Nutrient Agar surface using sterile bent glass rod which was incubated at 37\u0026deg;C for 24 h. After incubation morphologically different colonies were selected for subculture for further screening process [\u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\n \u003ch2\u003e2.3 Primary screening with Sudan Black B\u003c/h2\u003e\n \u003cp\u003eThe sub-cultured isolates were streaked on carbon-enriched agar medium consisting of 6.0g of Na\u003csub\u003e2\u003c/sub\u003eHPO\u003csub\u003e4\u003c/sub\u003e, 3.0g KH\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e, 1.0g NH\u003csub\u003e4\u003c/sub\u003eCl, 0.05g yeast extract, 0.5g NaCl, 17g agar-agar, and 10g glucose per liter solution. The pH of the medium was adjusted to 7.0 and after streaking the plates were incubated for 24h at 37\u0026deg;C. After incubation, the primary screening for the PHA producing bacterial colonies was performed by pouring 0.02% alcoholic solution of SBB on the plates which were left undisturbed for 20 minutes. The excess dye was carefully decanted without disturbing the colonies and the plates were rinsed by addition of absolute ethanol. The colonies positive for PHA production appeared bluish black by incorporation of SBB while colonies negative for PHA appeared white [\u003cspan class=\"CitationRef\"\u003e38\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\n \u003ch2\u003e2.4 Secondary screening for PHA production\u003c/h2\u003e\n \u003cp\u003eThe selected positive strains after primary screening were qualitatively screened, in duplicate, using PHA detecting agar (PDA) containing Nile Blue A (NBA) stain which has the following composition: 4g Nutrient Broth, 10g Nutrient Agar, and 0.25mg NBA for 500 ml solution. The streaked plates after incubation at 37\u0026deg;C for 24h were illuminated under UV light at 312 nm using UV Transilluminator, where the presence of PHA accumulation was indicated by bright orange fluorescence. The strains with orange fluorescence were selected for further processing [\u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\n \u003ch2\u003e2.5 Identification of selected isolates\u003c/h2\u003e\n \u003cp\u003eThe selected strains with ability to produce PHA were characterized by using morphological and biochemical examinations. The morphological character of bacterial isolates along with Gram reaction test were determined for performing various biochemical tests such as catalase, oxidase, citrate utilization, indole production test, urease activity, and carbohydrate utilization tests [\u003cspan class=\"CitationRef\"\u003e24\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n \u003ch2\u003e2.6 Inoculum preparation\u003c/h2\u003e\n \u003cp\u003eThe inoculum preparation was performed using 10 ml sterile Nutrient broth where a loopful of pure culture was inoculated and then incubated overnight at 37\u0026deg;C at 120 rpm shaking speed in shaker incubator. This liquid culture was used as inoculum or seed culture for further study [\u003cspan class=\"CitationRef\"\u003e38\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\n \u003ch2\u003e2.7 Submerged fermentation for PHA production\u003c/h2\u003e\n \u003cp\u003eThe selected strains were subjected to submerged fermentation using Mineral Salt Medium (MSM) containing (g/L): 40g glucose, 1.0g urea, 0.52g MgSO\u003csub\u003e4\u003c/sub\u003e, 0.02g CaCl\u003csub\u003e2\u003c/sub\u003e, 4.0g Na\u003csub\u003e2\u003c/sub\u003eHPO\u003csub\u003e4\u003c/sub\u003e, 0.16g yeast extract and 0.1 ml of trace element solution. The trace element solution was prepared by incorporating 5g of FeSO\u003csub\u003e4\u003c/sub\u003e.7H\u003csub\u003e2\u003c/sub\u003eO, 1.1245g of ZnSO\u003csub\u003e4\u003c/sub\u003e.7H\u003csub\u003e2\u003c/sub\u003eO, 0.5g of CuSO\u003csub\u003e4\u003c/sub\u003e.5H\u003csub\u003e2\u003c/sub\u003eO, 0.25g of MnSO\u003csub\u003e4\u003c/sub\u003e.5H\u003csub\u003e2\u003c/sub\u003eO, 1g of CaCl\u003csub\u003e2\u003c/sub\u003e.2H\u003csub\u003e2\u003c/sub\u003eO, 0.115g of Na\u003csub\u003e2\u003c/sub\u003eB\u003csub\u003e4\u003c/sub\u003eO\u003csub\u003e7\u003c/sub\u003e.10H\u003csub\u003e2\u003c/sub\u003eO, and 0.05g of (NH\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003eMo\u003csub\u003e7\u003c/sub\u003eO\u003csub\u003e24\u003c/sub\u003e in 500 ml distilled water [\u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e38\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\n \u003ch2\u003e2.8 Extraction of PHA\u003c/h2\u003e\n \u003cp\u003eThe extraction of PHA was performed using modified gravimetric analysis method. The fermented medium of selected strains was centrifuged at 5000 rpm for 30 minutes to obtain the cell biomass which was performed in triplicate. The biomass was dried at 40\u0026ndash;50\u0026deg;C which was weighed and was treated with 6.25 M NaCl solution at 37\u0026deg;C for 1h to recover the PHA. The content was then centrifuged at 5000 rpm for 15 minutes at room temperature and then the pellets were washed three times with distilled water and was again centrifuged at 5000 rpm for 10 minutes. the recovered pellets were then suspended in NaClO (4%, v/v) and chloroform at 1:1 (v/v) ratio. The suspension was incubated at 37\u0026deg;C for 1h and the mixture was centrifuged at 5000 rpm for 30 mins. After centrifugation, three distinct phases were obtained with upper phase of hypochlorite solution, middle phase with non-PHA cell mass and bottom phase of chloroform with PHA. The upper layer was removed by pipetting with the help of micropipette while the middle layer was filtered using Whatman filter paper. The chloroform suspension was then added with hexane (100%) (v/v) for the precipitation of PHA content which was recovered by drying at 40\u0026ndash;50\u0026deg;C by removing the traces of chloroform and hexane [\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\n \u003ch2\u003e2.9 Cell weight determination and PHA yield\u003c/h2\u003e\n \u003cp\u003eThe PHA content recovered was quantified in terms of percentage production (%PHA) in cell dry weight (CDW) which was calculated as ratio between total dry weight of PHA to CDW. The following formulas were applied for the quantification: [\u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e]\u003c/p\u003e\n \u003cp\u003eCell dry weight (CDW)\u0026thinsp;=\u0026thinsp;weight of the falcon tube with dried pellets \u0026ndash; weight of the empty falcon tube\u003c/p\u003e\n \u003cp\u003eDry weight of extracted PHA\u0026thinsp;=\u0026thinsp;weight of falcon tube with dried PHA \u0026ndash; weight of empty falcon tube\u003c/p\u003e\n \u003cdiv id=\"Equa\" class=\"Equation\"\u003e\n \u003cdiv class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e$$\\:\\text{%}\\text{P}\\text{H}\\text{A}=\\:\\frac{\\text{P}\\text{H}\\text{A}\\:\\text{w}\\text{e}\\text{i}\\text{g}\\text{h}\\text{t}\\:\\times\\:100}{\\text{D}\\text{r}\\text{y}\\:\\text{w}\\text{e}\\text{i}\\text{g}\\text{h}\\text{t}\\:\\text{o}\\text{f}\\:\\text{w}\\text{h}\\text{o}\\text{l}\\text{e}\\:\\text{c}\\text{e}\\text{l}\\text{l}}$$\u003c/div\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003e2.10 Optimization for PHA production\u003c/h2\u003e\u003cdiv id=\"Sec13\" class=\"Section3\"\u003e\u003ch2\u003e2.10.1 Effect of carbon source\u003c/h2\u003e\u003cp\u003eThe selected strains for optimization were initially cultured in Nutrient broth medium at 37\u0026deg;C, 120rpm for 24h. Subsequently, it was transferred to 50 ml MSM medium containing 2% w/v concentration of glucose, fructose, sucrose, and maltose as test carbon sources. The physical parameters including temperature (37\u0026deg;C), pH (7), and agitation speed (120 rpm) was maintained constantly throughout the process. After fermentation, the total biomass and PHA production were determined for each substrate in triplicate and the optimal carbon source was determined based on the highest PHA yield achieved [\u003cspan class=\"CitationRef\"\u003e38\u003c/span\u003e].\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec14\" class=\"Section3\"\u003e\u003ch2\u003e2.10.2 Effect of time\u003c/h2\u003e\u003cp\u003eThe optimization for the incubation time of the selected strains was also studied by incubating the strains in fermentation medium with glucose as sole carbon source for 24h, 48h, 72h, 96h, and 120h. The samples were extracted at these time interval in triplicate for determination of PHA yield [\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec15\" class=\"Section3\"\u003e\u003ch2\u003e2.10.3 Effect of pH\u003c/h2\u003e\u003cp\u003eThe effect of pH on the PHA production was also studied using different initial pH values of 5, 6, 7, 8, and 9 of the fermentation medium with glucose as carbon source. The estimation of PHA yield was performed in triplicate after incubation in pH range at 37\u0026deg;C for 72h [\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e38\u003c/span\u003e].\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec16\" class=\"Section3\"\u003e\u003ch2\u003e2.10.4 Effect of temperature\u003c/h2\u003e\u003cp\u003eThe physical variable incubation temperature was also optimized for the PHA production by incubating the selected strains in the fermentation medium with glucose as carbon source over a range of temperature which were 25\u0026deg;C, 30\u0026deg;C, 35\u0026deg;C, and 40\u0026deg;C. After incubation at this temperature for 72 h, the PHA production was estimated for each temperature in triplicate [\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e38\u003c/span\u003e].\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Sec17\" class=\"Section2\"\u003e\u003ch2\u003e2.11 UV-Visible spectrophotometry (Crotonic acid assay)\u003c/h2\u003e\u003cp\u003eThe crude PHA extracted was digested in 10ml of conc. H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e at 100\u0026deg;C (water bath) for 10 minutes. With the use of UV-Visible spectrophotometer, the preliminary identification of the PHA, the digested product was analyzed at 235 nm in the range of 200 to 800 nm; where H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e was used as blank [\u003cspan class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec18\" class=\"Section2\"\u003e\u003ch2\u003e2.12 FTIR analysis of PHA\u003c/h2\u003e\u003cp\u003eThe produced PHA was characterized by using Fourier Transform InfraRed spectroscopy where the obtained peak values were utilized to interpret the presence of specific functional groups in the biopolymer PHA [\u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec19\" class=\"Section2\"\u003e\u003ch2\u003e2.13 Preparation of PHA film\u003c/h2\u003e\u003cp\u003e50 mg of extracted PHA was dissolved in 1 ml of chloroform in a microfuge tube and the tube was placed in the oven at 50\u0026deg;C for complete vaporization of chloroform. The PHA films was obtained within the microfuge tube as result of evaporation of chloroform [\u003cspan class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec20\" class=\"Section2\"\u003e\u003ch2\u003e2.14 Statistical analysis\u003c/h2\u003e\u003cp\u003eThe experiments were carried out in triplicate and the values were recorded as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation using Microsoft Excel 2019 [\u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e]\u003c/p\u003e\u003c/div\u003e"},{"header":"3. Results and Discussion","content":"\u003cp\u003eEnvironmental samples such as soil, landfill, sewage sediments and compost were selected based on their variable traits as these sample maintain different microbial ecosystem. The samples were collected from different geographical areas of Nepal (Supplementary File, Section A). After processing by standard techniques, on observation of isolated bacterial colonies, 343 colonies\u0026nbsp;with\u0026nbsp;distinct\u0026nbsp;morphological\u0026nbsp;features\u0026nbsp;from\u0026nbsp;were\u0026nbsp;selected\u0026nbsp;for\u0026nbsp;further\u0026nbsp;screening\u0026nbsp;process\u0026nbsp;to\u0026nbsp;determine\u0026nbsp;their\u0026nbsp;ability\u0026nbsp;to\u0026nbsp;produce PHAs.\u003c/p\u003e\n\u003ch2\u003e3.1 Screening of PHA producing isolates\u003c/h2\u003e\n\u003cp\u003eA total of 343 bacterial isolates were initially screened for PHA accumulation using Sudan Black B (SBB) staining. Among them, 189 isolates exhibited bluish-black coloration, indicating positive lipid accumulation. In contrast, non-PHA producers retained their original whitish appearance after decolorization with absolute alcohol. The distribution of PHA accumulation isolates varied notably across environmental samples, with the highest abundance observed in sewage samples, followed by landfill, soil, and compost. The compost sample yielded the lowest number of positive isolates, although this did not necessarily correlate with the production efficiency. Geographical variability of PHA positive isolates is detailed in Supplementary File (Section A).\u003c/p\u003e\n\u003cp\u003eSudan Black B, a thermostable and lipophilic dye, effectively differentiates lipid containing colonies from non-producers, even with limited biomass. Despite variation in the degree of staining among positive colonies, the contrast with pale-stained negative colonies was distinct, \u0026nbsp;validating the dye\u0026rsquo;s utility in preliminary screening [12].\u003c/p\u003e\n\u003cp\u003eSubsequent secondary screening using Nile Blue A (NBA) refined the selection to 81 isolates (43% of SBB positive strains), which exhibited bright orange fluorescence under 312 nm UV light and regarded as true PHA producers (Figure 1). This two-step screening approach improved the specificity of isolate selection. This result aligns with previous studies [13], where a similar reduction in potential strains was observed after fluorescent based confirmation. Both SBB and NBA have been reported as reliable indicators for identifying PHA production in bacterial cells [12, 15, 19].\u003c/p\u003e\n\u003ch2\u003e3.2 Microscopic Characterization\u003c/h2\u003e\n\u003cp\u003eOn Gram\u0026rsquo;s staining, 72 isolates out of 81 (100%) were found to be Gram-positive whereas 9 isolates were Gram-negative (Figure 2). The Gram\u0026rsquo;s reaction of the all the isolates is provided in the Supplementary File, Section B.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe number of Gram-positive bacteria dominated the environment microflora as almost 90% of all the isolates were Gram-positive. This result show high degree of similarity with previous study by [17] reporting 56 Gram-positive bacteria with 38 being rods, 18 cocci, and 25 Gram-negative rods from various types of contaminated soil samples. Although there are limitations for literature reporting PHA production among Gram-negative cocci, some researchers have reported \u003cem\u003eAzotobacter\u003c/em\u003e spp., showing ability to accumulate PHA [7].\u003c/p\u003e\n\u003ch2\u003e3.3 Quantitative analysis of PHA production\u003c/h2\u003e\n\u003cp\u003eAmong\u0026nbsp;81\u0026nbsp;strains\u0026nbsp;utilized\u0026nbsp;for fermentation process, PHA yield was quantified for the 66 strains, while the remaining 15 strains did not yield determinable amounts of PHA. Upon analyzing\u0026nbsp;the\u0026nbsp;obtained\u0026nbsp;data,\u0026nbsp;the\u0026nbsp;yield\u0026nbsp;ratio\u0026nbsp;for\u0026nbsp;most\u0026nbsp;isolates\u0026nbsp;were\u0026nbsp;found\u0026nbsp;to\u0026nbsp;be\u0026nbsp;in the\u0026nbsp;lower\u0026nbsp;range while\u0026nbsp;only few\u0026nbsp;isolates produced PHA\u0026nbsp;in higher\u0026nbsp;ratio (Figure 3).\u003c/p\u003e\n\u003cp\u003eThe highest distribution of the isolates was observed in the range of 0-5% with 28 isolates while only 1 isolate was found to yield PHA in the range 20-25%. The isolate Nk3e was found to show the highest average yield of 22.748 \u0026plusmn; 3.608% while the lowest was demonstrated by the sample Nk3i with yield percentage of 0.273 \u0026plusmn; 0.067% by dry cell weight, which were both isolated from compost sample (Table 2). Despite limited literature, a study has reported the isolation of strain \u003cem\u003eCupriavidus\u003c/em\u003e spp., from compost, with ability to produce PHA content of 75.3% of dry cell weight, which was comparably higher than all the compost isolates from this study [42].\u003c/p\u003e\n\u003cp\u003eAmong other samples, the highest yield of PHA was obtained for the isolate Ht3d from soil with 12.76 \u0026plusmn; 1.854% (Table 1), Mn7d from landfill with 14.24 \u0026plusmn; 2.223% (Table 3), and Dg5c from sewage sample with 14.952 \u0026plusmn; 3.401% (Table 4). A study reported the \u003cem\u003eB. thuringiensis\u0026nbsp;\u003c/em\u003estrain isolated from the soil with PHA accumulation of 19% by weight of cell biomass, which was similar to the yield rate from soil isolate Ht3d [6]. Moreover, the study by [32] has reported the PHA yield as high as 57% and as low as 11.23% from different bacterial strains isolated from landfill sites, which upon comparison, the isolate in this study was found to have higher correlation with the lower yielding isolate. Similarly, the study by [26] isolated various bacterial strains from sewage sample with ability to yield PHA within the range of 5-30%, which shows relatively significant correlation with the sewage isolate Dg5c.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1:\u003c/strong\u003e Quantification of cell dry weight and PHA yield among Soil isolates\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 19.3878%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eName of Isolate\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25.5102%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eObserved PHA yield %\u003cbr\u003e\u0026nbsp;(Avg \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 29.5918%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCell Dry Weight (CDW)\u003cbr\u003e\u0026nbsp;(g/L)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14.2857%;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePHA Yield\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(g/L)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.2245%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e% Yield\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 19.3878%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHt3d\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25.5102%;\"\u003e\n \u003cp\u003e12.76\u0026plusmn;1.854\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 29.5918%;\"\u003e\n \u003cp\u003e0.31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14.2857%;\"\u003e\n \u003cp\u003e0.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.2245%;\"\u003e\n \u003cp\u003e12.817\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 19.3878%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSm5a\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25.5102%;\"\u003e\n \u003cp\u003e10.991\u0026plusmn;7.182\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 29.5918%;\"\u003e\n \u003cp\u003e0.367\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14.2857%;\"\u003e\n \u003cp\u003e0.036\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.2245%;\"\u003e\n \u003cp\u003e9.809\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 19.3878%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSy3b\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25.5102%;\"\u003e\n \u003cp\u003e7.035\u0026plusmn;1.456\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 29.5918%;\"\u003e\n \u003cp\u003e1.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14.2857%;\"\u003e\n \u003cp\u003e0.091\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.2245%;\"\u003e\n \u003cp\u003e7.689\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 19.3878%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSy3a\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25.5102%;\"\u003e\n \u003cp\u003e6.916\u0026plusmn;3.308\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 29.5918%;\"\u003e\n \u003cp\u003e0.657\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14.2857%;\"\u003e\n \u003cp\u003e0.044\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.2245%;\"\u003e\n \u003cp\u003e6.746\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 19.3878%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCG1a\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25.5102%;\"\u003e\n \u003cp\u003e6.925\u0026plusmn;1.727\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 29.5918%;\"\u003e\n \u003cp\u003e0.483\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14.2857%;\"\u003e\n \u003cp\u003e0.033\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.2245%;\"\u003e\n \u003cp\u003e6.724\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 19.3878%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCG1c\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25.5102%;\"\u003e\n \u003cp\u003e5.944\u0026plusmn;0.589\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 29.5918%;\"\u003e\n \u003cp\u003e0.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14.2857%;\"\u003e\n \u003cp\u003e0.035\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.2245%;\"\u003e\n \u003cp\u003e5.881\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 19.3878%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHt3g\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25.5102%;\"\u003e\n \u003cp\u003e5.656\u0026plusmn;2.296\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 29.5918%;\"\u003e\n \u003cp\u003e3.967\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14.2857%;\"\u003e\n \u003cp\u003e0.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.2245%;\"\u003e\n \u003cp\u003e5.286\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 19.3878%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHt5a\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25.5102%;\"\u003e\n \u003cp\u003e4.387\u0026plusmn;1.513\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 29.5918%;\"\u003e\n \u003cp\u003e0.893\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14.2857%;\"\u003e\n \u003cp\u003e0.038\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.2245%;\"\u003e\n \u003cp\u003e4.276\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 19.3878%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSm3f\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25.5102%;\"\u003e\n \u003cp\u003e3.466\u0026plusmn;0.837\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 29.5918%;\"\u003e\n \u003cp\u003e0.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14.2857%;\"\u003e\n \u003cp\u003e0.034\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.2245%;\"\u003e\n \u003cp\u003e3.446\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 19.3878%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCG5a\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25.5102%;\"\u003e\n \u003cp\u003e2.309\u0026plusmn;0.675\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 29.5918%;\"\u003e\n \u003cp\u003e3.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14.2857%;\"\u003e\n \u003cp\u003e0.068\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.2245%;\"\u003e\n \u003cp\u003e2.249\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 19.3878%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCG3c\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25.5102%;\"\u003e\n \u003cp\u003e2.259\u0026plusmn;1.891\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 29.5918%;\"\u003e\n \u003cp\u003e7.407\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14.2857%;\"\u003e\n \u003cp\u003e0.157\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.2245%;\"\u003e\n \u003cp\u003e2.121\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 19.3878%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCG1b\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25.5102%;\"\u003e\n \u003cp\u003e1.132\u0026plusmn;0.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 29.5918%;\"\u003e\n \u003cp\u003e4.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14.2857%;\"\u003e\n \u003cp\u003e0.053\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.2245%;\"\u003e\n \u003cp\u003e1.131\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e*Yield not determined among soil: Sm3e, Ht3a, Ht3b, Ht3c, Ht3f, Ht5f\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2:\u003c/strong\u003e Quantification of cell dry weight and PHA yield among Compost isolates\u003c/p\u003e\n\u003cdiv align=\"center\"\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eName of Isolate\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eObserved PHA yield %\u003cbr\u003e\u0026nbsp;(Avg \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCell Dry Weight (CDW) (g/L)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePHA yield (g/L)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e% Yield\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK3e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e22.748\u0026plusmn;3.608\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e2.467\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e0.543\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e22.014\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK3f\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e18.866\u0026plusmn;2.704\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e1.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e0.318\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e18.706\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBn6b\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e18.492\u0026plusmn;2.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e1.733\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e0.314\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e18.135\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBn6a\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e17.983\u0026plusmn;3.443\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e1.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e0.315\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e17.481\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eKS3a\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e13.866\u0026plusmn;2.263\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e4.367\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e0.585\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e13.405\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBt3c\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e12.813\u0026plusmn;3.475\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e2.267\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e0.291\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e12.853\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK3c\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e8.054\u0026plusmn;0.647\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e0.307\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e0.025\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e8.033\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBt3b\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e8.566\u0026plusmn;1.534\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e0.62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e0.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e8.005\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK3i\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e4.963\u0026plusmn;1.227\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e0.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e0.048\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e4.948\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBt3l\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e3.612\u0026plusmn;1.015\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e1.579\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e0.579\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e3.669\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBt3m\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e4.177\u0026plusmn;2.434\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e0.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e0.028\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e3.578\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBt3e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e3.02\u0026plusmn;1.288\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e2.367\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e0.067\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e2.852\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK3a\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e2.154\u0026plusmn;1.257\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e1.503\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e0.031\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e2.042\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBt3g\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e1.112\u0026plusmn;0.607\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e3.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e0.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e0.976\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNK3g\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e0.273\u0026plusmn;0.067\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e0.983\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e0.026\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 0%;\"\u003e\n \u003cp\u003e0.265\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e*Yield not determined among Compost: Ks3b, Bt3h\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3:\u003c/strong\u003e Quantification of cell dry weight and PHA yield among Landfill isolates\u003c/p\u003e\n\u003cdiv align=\"center\"\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eName of Isolate\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eObserved PHA yield %\u003cbr\u003e\u0026nbsp;(Avg \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCell Dry Weight (CDW)\u003cbr\u003e\u0026nbsp;(g/L)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePHA yield (g/L)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e% Yield\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMn7d\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e14.24\u0026plusmn;2.223\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e3.767\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.533\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e14.15\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMn7c\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e13.978\u0026plusmn;3.263\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e3.967\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.548\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e13.824\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMn5e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e12.572\u0026plusmn;0.493\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e3.567\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.447\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e12.542\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMn7b\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e11.901+1.002\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.478\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e11.942\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBl3a\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e11.686\u0026plusmn;0.631\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e3.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.408\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e11.667\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMn3e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e9.937\u0026plusmn;1.407\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e0.52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.048\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e9.288\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMn3d\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e7.903\u0026plusmn;1.068\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e0.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.044\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e7.795\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMn3a\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e6.582\u0026plusmn;3.308\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e0.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.035\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e6.541\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMn7a\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e6.41\u0026plusmn;0.782\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e0.69\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.044\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e6.396\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSb3a\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e6.257\u0026plusmn;2.617\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e3.567\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.203\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e5.682\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSb3c\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e2.716\u0026plusmn;0.161\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e2.237\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.061\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e2.717\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSb3j\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e2.281\u0026plusmn;0.321\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e0.413\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e2.379\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMn3f\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e2.181\u0026plusmn;0.651\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e0.713\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.015\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e2.033\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNz7a\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e1.824\u0026plusmn;0.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e3.043\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.052\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e1.705\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e*Yield not determined among Landfill isolates: Bl3d\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 4:\u003c/strong\u003e Quantification of cell dry weight and PHA yield among Sewage isolates\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eName of Isolate\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eObserved PHA yield %\u003cbr\u003e\u0026nbsp;(Avg \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCell Dry Weight (CDW)\u0026nbsp;\u003cbr\u003e\u0026nbsp;(g/L)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePHA yield (g/L)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e% Yield\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDg5c\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e14.952\u0026plusmn;3.401\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e3.233\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.458\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e14.17\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDg3d\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e11.729\u0026plusmn;1.063\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e0.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.041\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e11.96\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTk3g\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e11.988\u0026plusmn;0.693\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e0.383\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.045\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e11.69\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDg3j\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e9.083\u0026plusmn;1.583\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e1.333\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.132\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e9.875\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eKr3p\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e8.528\u0026plusmn;3.028\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e0.32\u003c/p\u003e\n \u003c/td\u003e\n 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valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.023\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e6.394\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eKr3u\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e7.278\u0026plusmn;2.327\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e0.453\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.028\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e6.213\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n 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valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.025\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e5.074\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTK3h\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e5.199\u0026plusmn;2.289\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e0.623\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.031\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e5.032\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n 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valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e4.186\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eKr3f\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e4.034\u0026plusmn;0.478\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e0.31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.013\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e4.097\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n 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valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.038\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e3.805\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eJr3f\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e3.958\u0026plusmn;1.782\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e0.413\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.013\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e3.169\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n 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valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e2.815\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDg3n\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e2.762\u0026plusmn;1.012\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e1.433\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.035\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e2.456\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDg3k\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e2.93\u0026plusmn;1.836\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e0.177\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.004\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e2.283\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTk3c\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e2.571\u0026plusmn;1.052\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e1.447\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e2.046\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eKr3g\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e1.909\u0026plusmn;0.467\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e0.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.014\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e1.625\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eKr3m\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.4898%;\"\u003e\n \u003cp\u003e1.389\u0026plusmn;0.334\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28.5714%;\"\u003e\n \u003cp\u003e4.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.3673%;\"\u003e\n \u003cp\u003e0.058\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.2041%;\"\u003e\n \u003cp\u003e1.337\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e*Yield not determined among Sewage isolates: Kr3a, Kr3d, Jr3a, Jr3h, Jr5c, Jr5e\u003c/p\u003e\n\u003cp\u003eFrom the results, it can be duly noted that bacteria isolated from compost are capable of higher yields of PHAs as compared to those of soil, sewage and landfill samples. Primarily, these differences in PHA yield are due to the variability in sample sites which mostly involved the divergence in microbial ecology along with additional metabolic variables such as temperature, aeration, and pH. The higher accumulation among compost isolates can also be attributed to several environmental and biological factors which are unique to compost ecosystems, such as high C:N ratio, nutrient rich environment, and thermophilic and aerobic condition [ 4, 35, 36].\u003cbr\u003e\u0026nbsp;\u003c/p\u003e\n\u003ch2\u003e3.4 Morphological and Biochemical characterization\u0026nbsp;\u003c/h2\u003e\n\u003cp\u003eFrom the total of 81 isolates, 4 of the isolates were selected for biochemical profiling determined based on the highest yielding strains from each sample type. The selected strain from soil sample Ht3d was determined to be\u0026nbsp;\u003cem\u003eBacillus circulans\u003c/em\u003e, Nk3e from compost as\u0026nbsp;\u003cbr\u003e\u003cem\u003eBacillus subtilis\u003c/em\u003e, Mn7d from landfill as \u003cem\u003eStaphylococcus aureus\u003c/em\u003e, while Dg5c from sewage sample was inferred as \u003cem\u003eStaphylococcus\u0026nbsp;\u003c/em\u003espp (Table 5)\u003cem\u003e.\u0026nbsp;\u003c/em\u003ewhich was identified using Bergey\u0026rsquo;s Manual of Determinative Bacteriology (Supplementary File, Section C).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 5\u003c/strong\u003e: Morphological and Biochemical profiling of selected isolates\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 32px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"4\" valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eIsolates\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 32px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTests\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003eHt3d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003eNk3e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003eMn7d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003eDg5c\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 32px;\"\u003e\n \u003cp\u003eGram staining\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003ePositive rod\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003ePositive rod\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003ePositive cocci\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003ePositive cocci\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 32px;\"\u003e\n \u003cp\u003eCatalase\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 32px;\"\u003e\n \u003cp\u003eOxidase\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 32px;\"\u003e\n \u003cp\u003eCoagulase\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 32px;\"\u003e\n \u003cp\u003eMannitol fermentation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 32px;\"\u003e\n \u003cp\u003ePigment\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003eGolden\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 32px;\"\u003e\n \u003cp\u003eStarch hydrolysis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 32px;\"\u003e\n \u003cp\u003eVP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 32px;\"\u003e\n \u003cp\u003eSpore\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 32px;\"\u003e\n \u003cp\u003eCell diameter \u0026ge;1\u0026micro;m\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 32px;\"\u003e\n \u003cp\u003eCitrate utilization\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 32px;\"\u003e\n \u003cp\u003eGrowth at 6.5% NaCl\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 32px;\"\u003e\n \u003cp\u003eGrowth at 55\u003csup\u003e0\u0026nbsp;\u003c/sup\u003eC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 32px;\"\u003e\n \u003cp\u003eAcid from arabinose\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 32px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e\u003cem\u003eBacillus circulans\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e\u003cem\u003eBacillus subtilis\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e\u003cem\u003eStaphylococcus aureus\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e\u003cem\u003eStaphylococcus\u0026nbsp;\u003c/em\u003espp.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003ePositive (+), Negative (-), Not determined (*)\u0026nbsp;\u003c/p\u003e\n\u003ch2\u003e3.5 Optimization\u003c/h2\u003e\n\u003cp\u003eThe selected isolates for each sample with the highest yield were further processed for determining the optimal condition of PHA production. Parameters such as carbon sources, time, pH, and temperature were\u0026nbsp;manipulated\u0026nbsp;at\u0026nbsp;different\u0026nbsp;levels\u0026nbsp;one\u0026nbsp;at\u0026nbsp;a\u0026nbsp;time,\u0026nbsp;for\u0026nbsp;determining\u0026nbsp;their\u0026nbsp;optimal level required for maximum yield of PHA.\u003c/p\u003e\n\u003ch3\u003e3.5.1 Optimization of carbon sources\u003c/h3\u003e\n\u003cp\u003eCarbohydrates serve as primary carbon sources for bacterial growth and PHA production, and different sugars can be metabolized at varying efficiencies depending on the bacterial strain and its enzymatic machinery [28]. After fermentation at constant temperature of 37\u0026deg;C, pH 7, and agitation speed of 120 rpm, the cell dry weight and PHA yield for each sample were determined.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eEach isolate exhibits a distinct preference for specific carbohydrates for maximum PHA production (Table 6). The highest yield of PHA with respect to cell dry weight was observed for the sample Ht3d which yielded 34.99 \u0026plusmn; 5.61% of PHA with 2.4 g/L of cell biomass utilizing the glucose carbon source followed by isolate Nk3e with 24.26 \u0026plusmn; 9.74% PHA yield and 4.17 g/L cell biomass from same carbon source. The isolate Mn7d was observed to show relatively high PHA yield for the substrate sucrose. Similarly, the sewage isolate Dg5c was observed to have higher affinity towards maltose substrate as compared to other isolates. With context to optimization for carbon substrate, the findings from research by [21] presented different strains of Bacillus spp., to yield maximum PHA from glucose and molasses which were 49.46 \u0026plusmn; 2.79% and 45.86 \u0026plusmn; 2.17% respectively. Meanwhile, some studies have reported prominent production of polyhydroxyalkanoates from both carbon sources, sucrose and glucose, using different strains of Bacillus spp. upon optimization, which was parallel to this study [20].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 6:\u003c/strong\u003e Determination of cell dry weight and PHA yield after optimization of carbon\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCarbon Source\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eIsolate\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eObserved PHA yield %\u003cbr\u003e\u0026nbsp;(Avg \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCell Dry Weight (CDW) (g/L)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePHA yield (g/L)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e% Yield\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGlucose\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003eHt3d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e34.99\u0026plusmn;5.61\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e2.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0.823\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003e34.305\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003eMn7d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e10.37\u0026plusmn;2.54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e3.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0.402\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003e10.134\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003eNk3e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e24.26\u0026plusmn;9.74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e4.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e1.011\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003e24.264\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003eDg5c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e4.03\u0026plusmn;2.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0.037\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003e4.306\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSucrose\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003eHt3d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e7.44\u0026plusmn;1.69\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0.0493\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003e7.4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003eMn7d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e18.85\u0026plusmn;3.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e3.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0.5853\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003e18.88\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003eNk3e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e13.85\u0026plusmn;0.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e3.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0.511\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003e13.81\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003eDg5c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e3.88\u0026plusmn;0.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e1.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0.0484\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003e3.83\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFructose\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003eHt3d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e4.33\u0026plusmn;1.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e1.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0.0529\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003e4.146\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003eMn7d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e9.91\u0026plusmn;2.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e5.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0.484\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003e9.367\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003eNk3e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e17.97\u0026plusmn;2.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e4.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0.7783\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003e17.425\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003eDg5c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e10.88\u0026plusmn;4.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e5.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0.5913\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003e10.19\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMaltose\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003eHt3d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e6.401\u0026plusmn;2.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0.0451\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003e6.04\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003eMn7d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e4.97\u0026plusmn;0.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0.0472\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003e4.92\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003eNk3e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e2.47\u0026plusmn;0.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e2.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0.0465\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003e2.036\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003eDg5c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e7.31\u0026plusmn;4.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e1.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0.0784\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003e7.35\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003e3.5.2 Optimization of pH\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOptimal pH conditions are crucial for maximizing PHA yield, as pH affects enzyme activity, nutrient availability, and overall bacterial growth. After fermentation at constant temperature of 37\u0026deg;C, glucose as carbon source, and agitation speed of 120 rpm, the cell dry weight and PHA yield for each sample were determined.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 7:\u003c/strong\u003e Determination of cell dry weight and PHA yield after optimization of pH\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6px;\"\u003e\n \u003cp\u003e\u003cstrong\u003epH\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eIsolate\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eObserved PHA yield %\u003cbr\u003e\u0026nbsp;(Avg \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 30px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCell Dry Weight (CDW) (g/L)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePHA yield (g/L)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e% Yield\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 6px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e5\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003eHt3d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e7.902\u0026plusmn; 1.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 30px;\"\u003e\n \u003cp\u003e2.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.196\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e7.724\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003eNk3e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e7.48\u0026plusmn;0.873\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 30px;\"\u003e\n \u003cp\u003e4.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.321\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e7.449\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003eDg5c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e8.37\u0026plusmn;0.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 30px;\"\u003e\n \u003cp\u003e4.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.379\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e8.25\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003eMn7d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e12.7\u0026plusmn;1.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 30px;\"\u003e\n \u003cp\u003e3.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.389\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e12.57\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 6px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e6\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003eHt3d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e15.7\u0026plusmn;1.68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 30px;\"\u003e\n \u003cp\u003e2.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.364\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e15.37\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003eNk3e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e10.7\u0026plusmn;2.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 30px;\"\u003e\n \u003cp\u003e0.76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.079\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e10.44\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003eDg5c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e14.7\u0026plusmn;3.77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 30px;\"\u003e\n \u003cp\u003e2.87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.409\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e14.27\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003eMn7d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e7.87\u0026plusmn;1.61\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 30px;\"\u003e\n \u003cp\u003e4.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.359\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e7.28\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 6px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e7\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003eHt3d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e12.7\u0026plusmn;1.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 30px;\"\u003e\n \u003cp\u003e3.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.397\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e12.82\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003eNk3e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e21.7\u0026plusmn;2.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 30px;\"\u003e\n \u003cp\u003e3.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.826\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e21.73\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003eDg5c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e17.7\u0026plusmn;2.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 30px;\"\u003e\n \u003cp\u003e4.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.758\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e17.36\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003eMn7d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e14.7\u0026plusmn;2.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 30px;\"\u003e\n \u003cp\u003e3.77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.533\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e14.15\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 6px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e8\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003eHt3d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e1.37\u0026plusmn;0.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 30px;\"\u003e\n \u003cp\u003e2.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0345\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e1.33\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003eNk3e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e1.57\u0026plusmn;0.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 30px;\"\u003e\n \u003cp\u003e1.74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0265\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e1.52\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003eDg5c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e0.97\u0026plusmn;0.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 30px;\"\u003e\n \u003cp\u003e2.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0217\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e0.98\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003eMn7d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e0.67\u0026plusmn;0.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 30px;\"\u003e\n \u003cp\u003e2.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0163\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e0.615\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 6px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e9\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003eHt3d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e0.47\u0026plusmn;0.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 30px;\"\u003e\n \u003cp\u003e2.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.011\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e0.452\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003eNk3e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e1.47\u0026plusmn;0.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 30px;\"\u003e\n \u003cp\u003e0.807\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0117\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e1.454\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003eDg5c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e0.57\u0026plusmn;0.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 30px;\"\u003e\n \u003cp\u003e2.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0112\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e0.491\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003eMn7d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e0.47\u0026plusmn;0.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 30px;\"\u003e\n \u003cp\u003e2.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0103\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e0.459\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eThe data reveals that the isolates exhibit a distinct preference for slight acidic / neutral pH for maximum PHA production (Table 7). The maximum average PHA yield among the isolates was observed in pH 7, where Nk3e isolate produced highest yield of 21.09 \u0026plusmn; 2.64% with 3.8 g/L cell biomass. At pH 5, the isolate Mn7d showed higher affinity for PHA accumulation and cell biomass production at pH 5 rather than pH 7, which was 12.75 \u0026plusmn; 1.52% and 3.1 g/L. The yield ratio at alkaline pH 8 and 9 were found to be significantly\u0026nbsp;lower\u0026nbsp;for\u0026nbsp;all\u0026nbsp;isolates\u0026nbsp;as\u0026nbsp;compared\u0026nbsp;to\u0026nbsp;the\u0026nbsp;acidic\u0026nbsp;and\u0026nbsp;neutral\u0026nbsp;pH as the highest yield of 1.55 \u0026plusmn; 0.28% and 1.44 \u0026plusmn; 0.19% was obtained from isolate Nk3e at pH 8 and 9 respectively. Thus, the optimal production and accumulation of PHAs by bacterial isolates were observed around pH 7. The least of the yield was noted at pH 8 and pH 9 among all the isolates. This drastic reduction in PHA yields at pH 8 and pH 9 for all isolates indicates that alkaline conditions are unfavorable for PHA production. The reduction in PHA yield observed under extreme pH conditions may be attributed to disruptions in intracellular pH homeostasis caused by the external environment. A shift in environmental pH can influence intracellular conditions, potentially leading to enzyme instability, impaired metabolic flux, and redirection of energy towards maintaining pH balance rather than toward biosynthesis.\u003c/p\u003e\n\u003cp\u003eInterestingly, most of the isolates in this study exhibited relatively higher biomass accumulation under acidic conditions compared to alkaline ones, suggesting a degree of acid tolerance. However, higher biomass did not always correlate with higher PHA accumulation, implying that pH may have a differential effect on growth versus PHA biosynthetic pathways. The higher yield of PHA at neutral pH observed in this study shows high correlation with the previous studies by [28] and [13], reporting neutral pH to be favorable for maximum PHA accumulation. Researches have been found to suggest initial alkaline pH (pH 9) for the strain \u003cem\u003eEnsifer\u0026nbsp;\u003c/em\u003esp., to achieve maximum PHA yield directly affecting enzyme activities of PHA producing bacteria [14]. This further provides evidence that different bacterial strains have varying optimal pH levels for PHA production, which depends on the enzymatic integrity and activity at different pH conditions.\u0026nbsp;\u003c/p\u003e\n\u003ch3\u003e3.5.3 Optimization of Temperature\u003c/h3\u003e\n\u003cp\u003eTemperature is a crucial factor affecting enzyme activity, cell membrane fluidity, and microbial metabolism, thereby influencing PHA production [40].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 8:\u003c/strong\u003e Determination of cell dry weight and PHA yield after optimization of incubation temperature\u003c/p\u003e\n\u003cdiv align=\"center\"\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 19px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTemperature\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(\u0026deg;C)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eIsolate\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eObserved PHA yield %\u003cbr\u003e\u0026nbsp;(Avg \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCell Dry Weight (CDW) (g/L)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePHA yield (g/L)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e% Yield\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 19px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e25\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003eHt3d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e3.222\u0026plusmn;0.787\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.933\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.028\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e3.039\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003eNk3e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e4.890\u0026plusmn;0.686\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.657\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.029\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e4.416\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003eDg5c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e3.113\u0026plusmn;0.726\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.977\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.029\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e3.020\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003eMn7d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e2.713\u0026plusmn;0.614\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e1.073\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.028\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e2.590\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 19px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e30\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003eHt3d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e20.824\u0026plusmn;0.940\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.767\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.159\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e20.783\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003eNk3e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e5.211\u0026plusmn;0.744\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.623\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.032\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e5.176\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003eDg5c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e8.114\u0026plusmn;0.571\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e5.133\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.409\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e7.961\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003eMn7d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e20.514\u0026plusmn;3.022\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e2.467\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.497\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e20.162\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 19px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e35\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003eHt3d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e13.123\u0026plusmn;1.133\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e1.003\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.131\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e13.023\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003eNk3e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e21.653\u0026plusmn;1.829\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e2.067\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.443\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e21.452\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003eDg5c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e3.717\u0026plusmn;1.423\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.853\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.028\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e3.234\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003eMn7d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e2.259\u0026plusmn;0.337\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e1.447\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.032\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e2.205\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 19px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e40\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003eHt3d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e9.579\u0026plusmn;1.674\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.277\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.026\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e9.470\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003eNk3e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e4.319\u0026plusmn;1.014\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.650\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.027\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e4.113\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003eDg5c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e10.962\u0026plusmn;1.413\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e2.733\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.296\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e10.841\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 16px;\"\u003e\n \u003cp\u003eMn7d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20px;\"\u003e\n \u003cp\u003e3.390\u0026plusmn;0.631\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.793\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e0.026\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e3.324\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eDifferences in PHA accumulation across bacterial isolates according to their incubation temperature was evident in this study (Table 8). Lowest incubation temperature of 25\u0026deg;C was found to show lower PHA accumulation as compared to other incubation temperature during optimization. At 30\u0026deg;C, two isolates Ht3d and Mn7d were found to show similar level of PHA yield which were 20.82 \u0026plusmn; 0.94% and 20.51 \u0026plusmn; 2.47% with the cell biomass 0.77 g/L and 2.47 g/L respectively. The isolate Nk3e preferred the temperature of 35\u0026deg;C for PHA accumulation as it showed highest yield rate of 21.65 \u0026plusmn; 1.83% and 2.07 g/L of cell biomass whereas, the higher temperature of 40\u0026deg;C was found to be more suitable for the isolate Dg5c which produced 10.96 \u0026plusmn; 1.41% of PHA from 0.79 g/L of cell biomass.\u003c/p\u003e\n\u003cp\u003eFor three out of the four isolates (Ht3d, Mn7d and Dg5c), 30\u0026deg;C appears to be a favorable temperature for PHA production. This aligns with the typical temperature preference for mesophilic bacteria, which thrive and exhibit optimal enzyme activity around 30\u0026deg;C. The study by [40], reported the optimal incubation temperature in the range 30\u0026ndash;35\u0026deg;C, as the maximum PHA yield of 96.9% was achieved by the strain\u0026nbsp;\u003cbr\u003e\u003cem\u003eParaburkholderia\u0026nbsp;\u003c/em\u003esp. at 35\u0026deg;C, which shows positive correlation with this study as maximum yield was obtained for the sample Nk3e at same temperature. The reduced PHA yields at 25\u0026deg;C and 40\u0026deg;C for most isolates suggest that these temperatures are less optimal for PHA production. This reduction in PHA accumulation with increasing temperature from optimal range have been linked with the decrement of enzymatic activity of microorganisms with increasing temperature [26]. However, Dg5c\u0026rsquo;s high yield at 40\u0026deg;C indicates its adaptability to higher temperatures. Therefore, maintaining temperatures around 30\u0026deg;C for Ht3d and Mn7d, 35\u0026deg;C for Nk3e and 40\u0026deg;C for Dg5c would be ideal for maximizing PHA production.\u0026nbsp;\u003c/p\u003e\n\u003ch3\u003e3.5.4 Optimization of incubation time\u003c/h3\u003e\n\u003cp\u003eIncubation time is a crucial factor affecting bacterial growth phase, nutrient availability, and metabolic activity. All these parameters, affect and influence PHA production. PHAs yield at varying incubation times (24 hours, 48 hours, 72 hours, 96 hours and 120 hours) provides a valuable insight into the temporal dynamics of PHA synthesis.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 9:\u003c/strong\u003e Determination of cell dry weight and PHA yield after optimization of incubation time\u003c/p\u003e\n\u003cdiv align=\"center\"\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTime (h)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eIsolate\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eObserved PHA yield %\u003cbr\u003e\u0026nbsp;(Avg \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCell Dry Weight (CDW) (g/L)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePHA yield (g/L)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e% Yield\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e24\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eHt3d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003e12.69\u0026plusmn;1.182\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003e2.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e12.96\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eMn7d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003e26.52\u0026plusmn;5.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003e2.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.615\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e25.625\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eNk3e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003e1.105\u0026plusmn;0.239\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003e1.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0134\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e1.059\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eDg5c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003e6.84\u0026plusmn;1.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003e1.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.078\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e6.36\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e48\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eHt3d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003e27.58\u0026plusmn;7.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003e2.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.677\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e27.46\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eMn7d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003e21.43\u0026plusmn;2.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003e3.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.781\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e21.7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eNk3e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003e7.63\u0026plusmn;3.68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003e5.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.383\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e7.14\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eDg5c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003e7.37\u0026plusmn;2.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003e3.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.191\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e6.23\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e72\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eHt3d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003e2.37\u0026plusmn;0.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003e5.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.128\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e2.33\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eMn7d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003e15.19\u0026plusmn;1.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003e1.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e15.029\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eNk3e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003e6.21\u0026plusmn;1.84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003e5.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.342\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e6.14\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eDg5c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003e2.88\u0026plusmn;2.004\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e2.57\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e96\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eHt3d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003e2.19\u0026plusmn;0.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003e0.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0134\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e2.04\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eMn7d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003e4.07\u0026plusmn;1.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003e3.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.159\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e4.38\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eNk3e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003e21.74\u0026plusmn;2.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003e4.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e1.062\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e21.53\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eDg5c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003e2.156\u0026plusmn;1.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003e1.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0327\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e2.109\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e120\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eHt3d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003e0.68\u0026plusmn;0.312\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003e0.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0072\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e0.736\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eMn7d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003e0.39\u0026plusmn;0.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003e0.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0021\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e0.378\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eNk3e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003e3.92\u0026plusmn;0.796\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003e0.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0209\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e3.918\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eDg5c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003e1.03\u0026plusmn;1.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 28px;\"\u003e\n \u003cp\u003e1.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.0191\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e1.27\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eEach isolate exhibits a distinct time profile for maximum PHA production, as the PHA yield of all the isolates were found to differ with time (Table 9). The isolate Ht3d, among all isolates, produced highest yield 27.58 \u0026plusmn; 7.25% from 2.47 g/L cell biomass at 48 hours which drastically declined in subsequent time intervals. The isolate Nk3e almost gradually increased the PHA yield along the interval with highest yield of 21.74 \u0026plusmn; 2.18% and 4.93 g/L cell biomass at the 96 hours. The isolate Mn7d was found to show highest PHA accumulation at 24 hours with yield ratio of 26.52 \u0026plusmn; 5.36% and 2.4 g/L cell biomass which decreased gradually over the time interval. At the time interval of 120 hours, the overall production was found to diminish for all the isolates where Nk3e and Dg5c were the only isolate to maintain substantial amount of PHA yield and cell biomass. A study suggested the optimum time for the PHA accumulation in different bacterial strain to be 72 hours, after which there was decline in the production rate [28]. Another study suggested the highest production of PHA in strain of\u0026nbsp;\u003cbr\u003e\u003cem\u003eEnsifer\u0026nbsp;\u003c/em\u003esp., was achieved only after longer incubation time of 108 hours, where the bacteria produced 45.54% w/w of PHA from 3.82 g/L of cell dry weight [14]. The incubation time period of 48 hours appears to be the most favorable incubation time for PHA production for isolates Ht3d and Dg5c. This suggests that, PHA synthesis peaked during the late exponential or early stationary phase of growth considering these isolates. Similarly, the extended incubation times i.e., 96 hours and 120 hours, generally resulted in lower PHA yields for most isolates, except for Nk3e at 96 hours. This trend indicates that prolonged incubation may lead to nutrient depletion, accumulation of toxic metabolites or onset of cellular death, all of which, negatively impacts the PHA production. Therefore, maintaining incubation times around 48 hours for Ht3d and Dg5c, 96 hours for Nk3d and 24 hours for Mn7d would be ideal for maximizing the PHA production.\u0026nbsp;\u003c/p\u003e\n\u003ch2\u003e3.6 UV-Vis spectroscopy\u003c/h2\u003e\n\u003cp\u003eThe crude PHA obtained from different isolates were further processed for the production of Crotonic acid by treatment with concentrated Sulphuric acid at 100\u0026deg;C for 10 mins. The extracted sample was used for the preliminary identification of PHAs using UV-Visible spectroscopy, within a range of 200 to 800 nm, with concentrated sulfuric acid as the standard. Upon analyzing the absorbance value, an absorption maxima at 232.0 nm with an absorbance of 3.793 was noted (Figure 4).\u003c/p\u003e\n\u003cp\u003eLiterature has suggested the use of Crotonic acid for the qualitative identification or quantification of the PHA molecule through the utilization of its inherent absorbance characteristics, which show characteristic peak at 235 nm under standard condition [28, 38]. The characteristic peak obtained in this study at 232 nm shows similarity with the peak of standard Crotonic acid at 235 nm [34]. Similarly, another study reported the highest maxima at 235 nm and the absorbance around 3.0 which was similar to the value obtained in this study [20].\u0026nbsp;\u003c/p\u003e\n\u003ch2\u003e3.7 FT-IR analysis\u003c/h2\u003e\n\u003cp\u003eThe analysis was carried out over the spectral range of 4000 \u0026ndash; 400 cm\u003csup\u003e-1\u003c/sup\u003e for the determination of the functional group present on the extracted polymer (Figure 5).\u003csup\u003e\u0026nbsp;\u003c/sup\u003eThe FT-IR results were found to demonstrate transmittance peaks over a range of\u0026nbsp;wavenumber,\u0026nbsp;notably\u0026nbsp;3437\u0026nbsp;cm\u003csup\u003e-1\u003c/sup\u003e,\u0026nbsp;2931\u0026nbsp;cm\u003csup\u003e-1\u003c/sup\u003e,\u0026nbsp;1724\u0026nbsp;cm\u003csup\u003e-1\u003c/sup\u003e,\u0026nbsp;1379\u0026nbsp;cm\u003csup\u003e-1\u003c/sup\u003e,\u0026nbsp;and\u0026nbsp;1290\u0026nbsp;cm\u003csup\u003e-\u003c/sup\u003e \u003csup\u003e1\u003c/sup\u003e.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe peaks observed on the FT-IR spectra for the PHA molecules were identified to have various functional group such as hydroxyl group (O-H) represented by 3437.15 cm\u003csup\u003e-1\u003c/sup\u003e,\u0026nbsp;C-H\u0026nbsp;stretching\u0026nbsp;by\u0026nbsp;peak\u0026nbsp;2932\u0026nbsp;cm\u003csup\u003e-1\u003c/sup\u003e,\u0026nbsp;presence\u0026nbsp;of\u0026nbsp;symmetrical\u0026nbsp;CH3\u0026nbsp;by 2850.79 cm\u003csup\u003e-1\u003c/sup\u003e, ester group (C=O) at 1724.36 cm\u003csup\u003e-1\u003c/sup\u003e, followed by stretching groups\u0026nbsp;of\u0026nbsp;-CH2,\u0026nbsp;terminal\u0026nbsp;-CH3,\u0026nbsp;C-O-C,\u0026nbsp;and\u0026nbsp;C-CH3 at 1462.04, 1379.1, 1228.6, and\u0026nbsp;1060.8\u0026nbsp;cm\u003csup\u003e-1\u003c/sup\u003e respectively, which were cross referenced with various studies (Table 10). Moreover, multiple absorption peaks were observed between 1060 \u0026ndash; 600 cm\u003csup\u003e-1\u003c/sup\u003e region which was significantly similar to the report by [29], where such bands were observed between 1054.31 to 677.46 cm\u003csup\u003e-1\u003c/sup\u003e which were referred as C-O and C-C stretching in amorphous phase. A study has reported the FT-IR analysis of transmittance spectra of PHA with several peaks in the regions 3440 cm\u003csup\u003e-1\u003c/sup\u003e for -OH group, 2930 \u0026ndash; 2980 cm\u003csup\u003e-1\u003c/sup\u003e for C-H stretching of methyl (-CH3), and methylene (-CH2) group, and the region 1380 \u0026ndash; 970 cm\u003csup\u003e-1\u003c/sup\u003e attributed to C-C, C-H, and C-O group which upon comparison was found to be similar with spectra of the PHA analyzed in this study [14].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 10:\u003c/strong\u003e Characterization of FT-IR peaks for extracted PHA\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"90%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\" valign=\"top\" style=\"width: 99px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; Wavenumber cm\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003eCurrent Study\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003ePrevious Study\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eFunctional\u0026nbsp;Group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e3437.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e3438\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eO-H\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e[29]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e2931.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e2932\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eC-H\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e[18]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e2850.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e2852.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eSymmetrical\u0026nbsp;CH3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e[29]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e1724.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e1724\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eC=O\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e[11]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e1462.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e1453\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003e-CH2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e[11]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e1379.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e1378.69\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003e-CH3 (terminal)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e[29]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e1228.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e1223.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eC-O-C stretching\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e[26]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e1060.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e1058.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 29px;\"\u003e\n \u003cp\u003eC-CH3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e[26]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003ch2\u003e3.8 PHA film preparation\u003c/h2\u003e\n\u003cp\u003eA thin sheet like structure around the walls of the tube was obtained after the evaporation of chloroform, which upon analysis showed highly brittle and fragile nature. This nature of obtained biofilm also correlates with multiple literature studies [13, 22].\u0026nbsp;\u003c/p\u003e"},{"header":"4. Limitations of the study","content":"\u003cp\u003eThe PHA producing isolates were identified solely based on phenotypic and biochemical tests which cannot provide definitive taxonomic resolution. The use of generalized viable plate method might have excluded strains requiring specific conditions for PHA accumulation. Due to limited resources, polymer purification, detailed chemical characterization, and biodegradability assessments of the extracted PHA were not performed. Furthermore, optimization using alternative substrates such as agro-waste and broader extrinsic parameters and their comparison was limited by the project timeline.\u003c/p\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eDespite the variability in sample sources \u0026ndash; soil, compost, landfill, and sewage \u0026ndash; all environmental habitats yielded bacterial isolates capable of PHA production. Interestingly, compost yielded the fewest positive isolates but produced the highest-yielding strain (Nk3e), highlighting that sample type may not directly predict yield capacity. The top-performing isolates \u0026ndash; \u003cem\u003eBacillus circulans\u003c/em\u003e (Ht3d), \u003cem\u003eBacillus subtilis\u003c/em\u003e (Nk3e), \u003cem\u003eStaphylococcus aureus\u003c/em\u003e (Mn7d), and \u003cem\u003eStaphylococcus\u003c/em\u003e spp. (Dg5c) \u0026ndash; achieved maximum yields of 34.99% and 24.26% under optimized conditions. While these yields are promising for the environmental isolates, they remain below industrial benchmarks, which often exceed 50\u0026ndash;80% of dry cell weight using high efficiency strains such as \u003cem\u003eCupriavidus necator\u003c/em\u003e under fed-batch or bioreactor conditions. Nonetheless, the significance of this study lies in identifying native PHA producing bacteria from underexplored ecological niches of Nepal \u0026ndash; highlighting untapped biodiversity. Further work incorporating molecular identification, cost-effective scale-up strategies, and genetic or metabolic engineering could enhance both yield and feasibility for industrial application. The extracted biopolymer was successfully possessed into film and confirmed via UV-Vis and FT-IR analyses. These findings offer a foundational step toward sustainable bioplastic production using locally sourced strains, aligning with global efforts in circular bioeconomy and plastics alternative.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003ePHA Polyhydroxyalkanoate \u003c/p\u003e\n\u003cp\u003eSBB Sudan Black B\u003c/p\u003e\n\u003cp\u003eNBA Nile Blue A\u003c/p\u003e\n\u003cp\u003eFT-IR Fourier Transform - Infrared \u003c/p\u003e\n\u003cp\u003eUV- Vis Ultra Violet \u0026ndash; Visible\u003c/p\u003e\n\u003cp\u003eMt Million metric tons\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors confirm that the data supporting the findings of the study are available within the article and the supplementary files and can be contacted to the corresponding author.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research was self-funded by the authors and no external funding was provided.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor\u0026rsquo;s Contribution\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSA, SB, RS, and SSS, conceptualized the study; carried out the investigation, data acquisition, and interpretation of data. SA designed the work. SA, and SB collected essential resources and utilized software for visualization and interpretation; and also wrote the manuscript. UK supervised, and validated the study, and reviewed the manuscript. All the authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors would like to express sincere gratitude to the Department of Microbiology and\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;St. Xavier\u0026rsquo;s College for the provision of laboratory facilities during the study period. The authors are deeply indebted towards Mr. Sandesh Maharjan and Mr. Prakash Manandhar (Lecturer, St. Xavier\u0026rsquo;s College) for their valuable technical assistance during spectroscopy and centrifugation process. \u0026nbsp;The authors are also grateful to the Nepal Academy of Science and Technology (NAST) for providing the FT-IR Spectroscopy required for the study.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eAcharjee, S. A., Bharali, P., Gogoi, B., Sorhie, V., Walling, B., Alemtoshi., 2022. PHA-based bioplastic: a potential alternative to address microplastic pollution. Water Air Soil Pollut., 234(1), 1\u0026ndash;31. https://doi.org/10.1007/S11270-022-06029-2\u003c/li\u003e\n \u003cli\u003e\u0026Aacute;lvarez-Ch\u0026aacute;vez, C. R., Edwards, S., Moure-Eraso, R., Geiser, K., 2012. Sustainability of bio-based plastics: general comparative analysis and recommendations for improvement. J. Clean. Prod., 23(1), 47\u0026ndash;56. https://doi.org/10.1016/j.jclepro.2011.10.003\u003c/li\u003e\n \u003cli\u003eAragosa, A., Specchia, V., \u0026amp; Frigione, M., 2023. Valorization of waste from argan seeds for polyhydroxybutyrate production using bacterial strains isolated from argan soils. Polymers, 15(8), 1972. https://doi.org/10.3390/polym15081972\u003c/li\u003e\n \u003cli\u003eAzim, K., Soudi, B., Boukhari, S., Perissol, C., Roussos, S., Thami Alami, I., 2018. Composting parameters and compost quality: a literature review. Org. Agr., 8(2). https://doi.org/10.1007/s13165-017-0180-z\u003c/li\u003e\n \u003cli\u003eBhuwal, A. K., Singh, G., Aggarwal, N. K., Goyal, V., Yadav, A., 2013. Isolation and screening of polyhydroxyalkanoates producing bacteria from pulp, paper, and cardboard industry wastes. Int. J. Biomater., 2013. https://doi.org/10.1155/2013/752821\u003c/li\u003e\n \u003cli\u003eCueva-Almendras, L. C., Alvarado, J. C. A., Fuentes-Olivera, A. J., Llontop-Bernab\u0026eacute;, K. S., Cerna, C. E. Q., Rodriguez-Soto, J. C., Cruz-Monz\u0026oacute;n, J. A., Quezada Alvarez, M. A., 2022. Production of polyhydroxyalkanoate by \u003cem\u003eBacillus\u003c/em\u003e \u003cem\u003ethuringiensis\u003c/em\u003e isolated from agricultural soils of Cascas-Peru. Braz. Arch. Biol. Technol., 65. https://doi.org/10.1590/1678-4324-2022220107\u003c/li\u003e\n \u003cli\u003eEl-Nahrawy, S., Abd El-Kodoos, R. Y., Belal, E.-S. B., El-Shouny, W., 2018. Production of poly-\u0026beta;-hydroxybutyrate (PHB) by \u003cem\u003eAzospirillum\u003c/em\u003e and \u003cem\u003eRhizobium\u003c/em\u003e sp. EBSS, 2(2018), 1\u0026ndash;25. https://doi.org/10.21608/jenvbs.2019.6781.1044\u003c/li\u003e\n \u003cli\u003eGaur, V. K., Nguyen-Vo, T. P., Islam, T., Bassey, B. F., Kim, M., Ainala, S. K., Shin, K., \u0026amp; Park, S. (2024). Efficient bioproduction of poly(3-hydroxypropionate) homopolymer using engineered Escherichia coli strains. Bioresource Technology, 397, 130469. https://doi.org/10.1016/j.biortech.2024.130469\u003c/li\u003e\n \u003cli\u003eGeyer, R., Jambeck, J. R., Law, K. L., 2017. Production, use, and fate of all plastics ever made. Sci. Adv., 3(7). https://doi.org/10.1126/sciadv.1700782\u003c/li\u003e\n \u003cli\u003eGill, M. (2014). Bioplastic: a better alternative to plastics. Int. J. Res Appl. Nat. Soc. Sci., 2(8), 113\u0026ndash;118.\u003c/li\u003e\n \u003cli\u003eHamdy, S. M., Danial, A. W., Gad El-Rab, S. M. F., Shoreit, A. A. M., Hesham, A. E.-L., 2022. Production and optimization of bioplastic (Polyhydroxybutyrate) from \u003cem\u003eBacillus\u003c/em\u003e \u003cem\u003ecereus\u003c/em\u003e strain SH-02 using response surface methodology. BMC Microbiol., 22(1), 183. https://doi.org/10.1186/s12866-022-02593-z\u003c/li\u003e\n \u003cli\u003eHomolak, J., Joja, M., Markovic, P., Salkovic-Petrisic, M., 2022. Sudan black lipid blot \u0026ndash; a rapid and simple method for quantification of lipids in biological samples. BioRxiv. https://doi.org/https://doi.org/10.1101/2022.07.27.501748\u003c/li\u003e\n \u003cli\u003eJavaid, H., Nawaz, A., Riaz, N., Mukhtar, H., Ikram-Ul-haq, Shah, K. A., Khan, H., Naqvi, S. M., Shakoor, S., Rasool, A., Ullah, K., Manzoor, R., Kaleem, I., Murtaza, G., 2020. Biosynthesis of polyhydroxyalkanoates (PHAs) by the valorization of biomass and synthetic waste. Molecules, 25(23). https://doi.org/10.3390/molecules25235539\u003c/li\u003e\n \u003cli\u003eKhamkong, T., Penkhrue, W., Lumyong, S., 2022. Optimization of production of polyhydroxyalkanoates (PHAs) from newly isolated \u003cem\u003eEnsifer\u003c/em\u003e sp. strain HD34 by response surface methodology. Processes, 10(8). https://doi.org/10.3390/pr10081632\u003c/li\u003e\n \u003cli\u003eKitamura, S., Doi, Y., 1994. Staining method of poly(3-hydroxyalkanoic acids) producing bacteria by nile blue. Biotechnol. Tech., 8(5). https://doi.org/10.1007/BF02428979\u003c/li\u003e\n \u003cli\u003eKoller, M. (2020). Advances in polyhydroxyalkanoate (PHA) production, Volume 2. Bioeng., 7(1). https://doi.org/10.3390/bioengineering7010024\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eMascarenhas, J., Aruna, K., 2017. Screening of polyhydroxyalkonates (PHA) accumulating bacteria from diverse habitats. J. Glob. Biosci., 6(3), 4835\u0026ndash;4848. http://www.mutagens.co.in/jgb/vol.06/3/060304.pdf\u003c/li\u003e\n \u003cli\u003eMazwan, M., Febriani, F., Nazaruddin, N., 2023. Isolation and characterization of polyhydroxyalkanoate (PHA) producing bacteria isolate from landfill land of Kampung Jawa Banda Aceh. J. Nat., 23(1), 53\u0026ndash;61. https://doi.org/10.24815/jn.v23i1.29746\u003c/li\u003e\n \u003cli\u003eMesquita, D. P., Amaral, A. L., Leal, C., Oehmen, A., Reis, M. A. M., Ferreira, E. C., 2015. Polyhydroxyalkanoate granules quantification in mixed microbial cultures using image analysis: sudan black b versus nile blue a staining. Anal. Chim. Acta, 865(1). https://doi.org/10.1016/j.aca.2015.01.018\u003c/li\u003e\n \u003cli\u003eMhatre, K. J., Naik, V. A., 2022. Study of bacterial biopolymer production by \u003cem\u003eBacillus\u003c/em\u003e species. Int. J. Curr. Microbiol. Appl. Sci., 11(4), 21\u0026ndash;29. https://doi.org/10.20546/ijcmas.2022.1104.004\u003c/li\u003e\n \u003cli\u003eMohammed, S., Panda, A. N., Ray, L., 2019. An investigation for recovery of polyhydroxyalkanoates (PHA) from \u003cem\u003eBacillus\u003c/em\u003e sp. BPPI-14 and \u003cem\u003eBacillus\u003c/em\u003e sp. BPPI-19 isolated from plastic waste landfill. Int. J. Biol. Macromol., 134, 1085\u0026ndash;1096. https://doi.org/10.1016/j.ijbiomac.2019.05.155\u003c/li\u003e\n \u003cli\u003eMohammed, S., Ray, L., 2022. Polyhydroxyalkanoate recovery from newly screened \u003cem\u003eBacillus\u003c/em\u003e sp. LPPI-18 using various methods of extraction from Loktak Lake sediment sample. J. Genet. Eng. Biotechnol., 20(1), 115. https://doi.org/10.1186/S43141-022-00392-7\u003c/li\u003e\n \u003cli\u003eMoshood, T. D., Nawanir, G., Mahmud, F., Mohamad, F., Ahmad, M. H., AbdulGhani, A., 2022. Sustainability of biodegradable plastics: new problem or solution to solve the global plastic pollution? Curr. Res. Green Sustain. Chem., 5, 100273. https://doi.org/10.1016/J.CRGSC.2022.100273\u003c/li\u003e\n \u003cli\u003eMuigano, M. N., Anami, S. E., Onguso, J. M., Omare, G. M., 2023. The isolation, screening, and characterization of polyhydroxyalkanoate-producing bacteria from hypersaline lakes in Kenya. Bacteria, 2(2), 81\u0026ndash;97. https://doi.org/10.3390/BACTERIA2020007/S1\u003c/li\u003e\n \u003cli\u003eNikiema, J., Asiedu, Z., 2022. A review of the cost and effectiveness of solutions to address plastic pollution. Environ. Sci. Pollut. Res., 29(17), 24547\u0026ndash;24573. https://doi.org/10.1007/S11356-021-18038-5/TABLES/13\u003c/li\u003e\n \u003cli\u003eOdeniyi, O. A., Adeola, O. J., 2017. Production and characterization of polyhydroxyalkanoic acid from \u003cem\u003eBacillus\u003c/em\u003e \u003cem\u003ethuringiensis\u003c/em\u003e using different carbon substrates. Int. J. Biol. Macromol., 104, 407\u0026ndash;413. https://doi.org/10.1016/j.ijbiomac.2017.06.041\u003c/li\u003e\n \u003cli\u003ePandey, P., Dhiman, M., Kansal, A., \u0026amp; Subudhi, S. P. (2023). Plastic waste management for sustainable environment: techniques and approaches. Waste Dispos. Sustain. Energy, 5(2). https://doi.org/10.1007/s42768-023-00134-6\u003c/li\u003e\n \u003cli\u003ePatil, T. D., Ghosh, S., Agarwal, A., Patel, S. K. S., Tripathi, A. D., Mahato, D. K., Kumar, P., Slama, P., Pavlik, A., Haque, S., 2024. Production, optimization, scale up and characterization of polyhydoxyalkanoates copolymers utilizing dairy processing waste. Sci. Rep., 14(1), 1620. https://doi.org/10.1038/s41598-024-52098-0\u003c/li\u003e\n \u003cli\u003eRakkan, T., Chana, N., Sangkharak, K., 2022. The integration of textile wastewater treatment with polyhydroxyalkanoate production using newly isolated \u003cem\u003eEnterobacter\u003c/em\u003e strain TS3. Waste Biomass Valorization, 13(1), 571\u0026ndash;582. https://doi.org/10.1007/s12649-021-01504-z\u003c/li\u003e\n \u003cli\u003eRay, S., Jin, J. O., Choi, I., Kim, M., 2022. Recent trends of biotechnological production of polyhydroxyalkanoates from C1 carbon sources. Front. Bioeng. Biotechnol., 10. https://doi.org/10.3389/FBIOE.2022.907500\u003c/li\u003e\n \u003cli\u003eRaza, Z. A., Abid, S., Banat, I. M., 2018. Polyhydroxyalkanoates: characteristics, production, recent developments and applications. Int. Biodeterior. Biodegradation, 126, 45\u0026ndash;56. https://doi.org/10.1016/J.IBIOD.2017.10.001\u003c/li\u003e\n \u003cli\u003eRazak, W. W. A., Mohamad Yusuf, N., Abdul-Aziz, A., Navaratnam, S. K., Zubir, I., Rizlan Ross, E. E., 2019. Screening and isolation of polyhydroxyalkanoates (PHA)-producing bacteria from landfill by using cocoa pod husks as carbon source. Int. J. Eng. Technol., 7(4.14), 51-56. https://doi.org/10.14419/ijet.v7i4.14.27470\u003c/li\u003e\n \u003cli\u003eRhodes, C. J. (2018). Plastic pollution and potential solutions. Sci. Prog., 101(3), 207\u0026ndash;260. https://doi.org/10.3184/003685018X15294876706211\u003c/li\u003e\n \u003cli\u003eSalgaonkar, B., Bragan\u0026ccedil;a, J., 2017. Utilization of sugarcane bagasse by \u003cem\u003eHalogeometricum\u003c/em\u003e \u003cem\u003eborinquense\u003c/em\u003e strain E3 for biosynthesis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate). Bioeng., 4(2), 50. https://doi.org/10.3390/bioengineering4020050\u003c/li\u003e\n \u003cli\u003eS\u0026aacute;nchez, \u0026Oacute;. J., Ospina, D. A., Montoya, S., 2017. Compost supplementation with nutrients and microorganisms in composting process. J. Waste Manag., 69. https://doi.org/10.1016/j.wasman.2017.08.012\u003c/li\u003e\n \u003cli\u003eS\u0026aacute;nchez Valencia, A. I., Rojas Zamora, U., Meraz Rodr\u0026iacute;guez, M., \u0026Aacute;lvarez Ram\u0026iacute;rez, J., Salazar Pel\u0026aacute;ez, M. L., Fajardo Ortiz, C., 2021. Effect of C/N ratio on the PHA accumulation capability of microbial mixed culture fed with leachates from the organic fraction of municipal solid waste (OFMSW). JWPE, 40. https://doi.org/10.1016/j.jwpe.2021.101975\u003c/li\u003e\n \u003cli\u003eSathianachiyar, S., Devaraj, A., 2013. Biopolymer production by bacterial species using glycerol, a byproduct of biodiesel. Int. J. Sci. Res. Publ., 3(8).\u003c/li\u003e\n \u003cli\u003eShah, S., Kumar, A., 2021. Production and characterization of polyhydroxyalkanoates from industrial waste using soil bacterial isolates. Braz. J. Microbiol., 52(2), 715\u0026ndash;726. https://doi.org/10.1007/s42770-021-00452-z\u003c/li\u003e\n \u003cli\u003eSingh, P., Mahato, R. P., 2019. Screening of potential soil bacteria for detection of polyhydroxyalkanoate (PHA) accumulation. Int. J. Res. Advent Technol., 7(3).\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eSriyapai, T., Chuarung, T., Kimbara, K., Samosorn, S., Sriyapai, P., 2022. Production and optimization of polyhydroxyalkanoates (PHAs) from \u003cem\u003eParaburkholderia\u003c/em\u003e sp. PFN 29 under submerged fermentation. Electron. J. Biotechnol., 56. https://doi.org/10.1016/j.ejbt.2021.12.003\u003c/li\u003e\n \u003cli\u003eVermeer, C. M., Bons, L. J., Kleerebezem, R., 2022. Production of a newly discovered PHA family member with an isobutyrate-fed enrichment culture. Appl. Microbiol. Biotechnol., 106(2), 605. https://doi.org/10.1007/S00253-021-11742-9\u003c/li\u003e\n \u003cli\u003eYootoum, A., Jantanasakulwong, K., Rachtanapun, P., Moukamnerd, C., Chaiyaso, T., Pumas, C., Tanadchangsaeng, N., Watanabe, M., Fukui, T., Insomphun, C., 2023. Characterization of newly isolated thermotolerant bacterium \u003cem\u003eCupriavidus\u003c/em\u003e sp. CB15 from composting and its ability to produce polyhydroxyalkanoate from glycerol. Microb. Cell Fact., 22(1). https://doi.org/10.1186/s12934-023-02059-5\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-microbiology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"mcro","sideBox":"Learn more about [BMC Microbiology](http://bmcmicrobiol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/mcro","title":"BMC Microbiology","twitterHandle":"#bmcmicrobiology","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Polyhydroxyalkanoates, Nile Blue A, Sudan Black B, Bioplastic, Plastic pollution","lastPublishedDoi":"10.21203/rs.3.rs-5641446/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5641446/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe versatile non-biodegradable material plastic has significantly enhanced innovation, but its production heavily relies on fossil fuels and non-renewable resources, which causes severe pollution and ecosystem disruption, highlighting the urgent need for eco-friendly alternatives. Polyhydroxyalkanoates (PHA) are a class of bioplastics that offer a promising solution as biodegradable, environmentally compatible, and versatile biopolymer synthesized by microorganisms using various substrates, aiding in organic waste management. This study was aimed to isolate and profile PHA producing bacteria from diverse sources such as soil, compost, landfill site, and sewage in Nepal. The initial screening of bacteria was performed by Sudan Black B dye, followed by secondary screening with the more specific Nile Blue A dye to detect PHA accumulation. Out of 343 isolates, 81 were confirmed positive for PHA production which were further processed for PHA extraction. The isolates Ht3d (12.76\u0026thinsp;\u0026plusmn;\u0026thinsp;1.854%), Nk3e (22.748\u0026thinsp;\u0026plusmn;\u0026thinsp;3.608%), Mn7d (14.24\u0026thinsp;\u0026plusmn;\u0026thinsp;2.223%), and Dg5c (14.952\u0026thinsp;\u0026plusmn;\u0026thinsp;3.401%) from soil, compost, landfill, and sewage respectively, showed the highest PHA accumulation and were biochemically identified as \u003cem\u003eBacillus circulans\u003c/em\u003e, \u003cem\u003eBacillus subtilis\u003c/em\u003e,\u003c/p\u003e\u003cp\u003e\u003cem\u003eStaphylococcus aureus\u003c/em\u003e, \u003cem\u003eStaphylococcus\u003c/em\u003e spp., respectively. The yield ratio for isolate Ht3d significantly increased by 2.74 fold under the optimal conditions (pH 7, 35\u0026deg;C, and 48 h with glucose as carbon source) which was 34.99\u0026thinsp;\u0026plusmn;\u0026thinsp;5.61% having titer value of 0.82 g/L and production rate of 0.034 g/L/h with respect to 2.4 g/L of cell biomass. The production rate and dry cell weight of other isolates were also enhanced under different optimal conditions. The characterization of the produced biopolymer through UV-Visible spectrophotometry provided maximum absorbance at 232 nm and the FT-IR spectroscopy indicated the presence of O-H and C-H vibrations along with C\u0026thinsp;=\u0026thinsp;O, C-O-C stretching which collectively confirmed the presence of PHA.\u003c/p\u003e","manuscriptTitle":"Analysis and optimization of Polyhydroxyalkanoates production by environmental bacterial isolates from Nepal","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-06 05:31:08","doi":"10.21203/rs.3.rs-5641446/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Accepted","date":"2025-08-11T05:18:34+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-08-06T05:44:23+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Microbiology","date":"2025-08-04T15:24:32+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-microbiology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"mcro","sideBox":"Learn more about [BMC Microbiology](http://bmcmicrobiol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/mcro","title":"BMC Microbiology","twitterHandle":"#bmcmicrobiology","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"9d801856-7860-453f-9637-c6453325950b","owner":[],"postedDate":"August 6th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-09-01T16:00:54+00:00","versionOfRecord":{"articleIdentity":"rs-5641446","link":"https://doi.org/10.1186/s12866-025-04314-8","journal":{"identity":"bmc-microbiology","isVorOnly":false,"title":"BMC Microbiology"},"publishedOn":"2025-08-25 15:57:25","publishedOnDateReadable":"August 25th, 2025"},"versionCreatedAt":"2025-08-06 05:31:08","video":"","vorDoi":"10.1186/s12866-025-04314-8","vorDoiUrl":"https://doi.org/10.1186/s12866-025-04314-8","workflowStages":[]},"version":"v1","identity":"rs-5641446","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5641446","identity":"rs-5641446","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}