Halotolerant Bacteria From Camocim, Brazil: Prospects for Astrobiology and Biotechnology

Halotolerant Bacteria From Camocim, Brazil: Prospects for Astrobiology and Biotechnology | 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 Halotolerant Bacteria From Camocim, Brazil: Prospects for Astrobiology and Biotechnology Camila Souza Vieira, Jomar Lima Barros, Caio Issamu Somiza, Edmo Montes Rodrigues, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6958968/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Halotolerant bacteria possess significant scientific and biotechnological potential due to their ability to thrive in high-salinity environments and withstand other harsh conditions. Their adaptive mechanisms—such as the production of exopolysaccharides, specialized enzymes, and biosurfactants—enable applications in bioremediation, saline wastewater treatment, and industries like food, medicine, and detergents. Notably, these bacteria can tolerate not only NaCl but also other salts, including perchlorates, which are highly toxic and abundant on Mars, where they contribute to liquid water stability.In this study, we isolated halotolerant bacteria from underexplored sites in Camocim, Ceará, Brazil, and investigated their potential for biotechnological and astrobiological applications. We assessed their tolerance to NaCl and perchlorate, as well as their ability to produce biosurfactants, exopolysaccharides, and enzymes (amylase, lipase, and protease). Additionally, we evaluated their capacity to grow under anoxic conditions using sodium perchlorate as a terminal electron acceptor—a key trait for survival in Mars-like environments. Among the 20 isolates, predominantly identified as Bacillus sp., all tolerated NaCl concentrations up to 150 g L⁻¹, with Bacillus sp. CaSS7 growing at the maximum tested concentration of 200 g L⁻¹. Most strains also withstood sodium perchlorate at 110 g L⁻¹. Interestingly, NaCl and perchlorate tolerance were not correlated, suggesting distinct stress responses and cellular damage mechanisms for each salt. All isolates produced at least one tested enzyme, 16 synthesized exopolysaccharides, and five were biosurfactant producers. Furthermore, their ability to utilize perchlorate as an electron acceptor under anoxic conditions highlights their potential relevance in astrobiology. This study underscores the importance of expanding bioprospecting efforts to uncover novel applications of halotolerant bacteria and sets the foundation for future research in biotechnology and planetary science. Perchlorate reduction Enzymatic production Brazilian microorganisms Salt tolerance Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 INTRODUCTION The study of extremophiles has gained significant attention in recent years due to their diverse scientific and biotechnological applications, which result from their remarkable adaptations to harsh environments. Extremophiles can be classified into various categories based on the extreme conditions they are capable of withstanding. These categories include thermophiles, hyperthermophiles, psychrophiles, psychrotolerants, acidophiles, alkaliphiles, barophiles, halophiles, and halotolerants (Ali et al., 2023 ). Halotolerant bacteria are different from halophiles in that they do not require NaCl to live, but can withstand high concentrations of this salt (Larsen 1986 ). Non halophiles/non halotolerants are affected by high NaCl concentrations, losing cellular water by osmosis, but salt-tolerant microorganisms have adaptive mechanisms that allow them to survive under these extreme conditions (Mukhtar et al. 2020 ). The salt-in mechanism maintains the ionic concentration in the cell through ions symport, antiport, and active transport (Gunde-Cimerman et al. 2018 ). In contrast, the salt-out mechanism maintains the osmotic pressure through the synthesis or uptake of compatible solutes such as glycine betaine and trehalose (Ionescu et al. 2024). Another characteristic adaptation of halophiles is the higher number of acidic amino acids in their enzymes, compared to non-halophiles (Madern et al. 1995 ). These adapted enzymes have applications in various industry sectors. They can maintain activity not only at high salt concentrations but also at extreme pH levels and temperatures (Delgado-García et al. 2012 ). Halophilic enzymes can be used to treat saline wastewater. Lipases, amylases, and proteases have been studied for treating wastewater from the leather industry. This type of wastewater is rich in NaCl and mainly consists of lipids, mucopolysaccharides, and proteins (Maharaja et al. 2020 ). Enzymatic wastewater treatment is more effective than chemical treatment due to faster reaction kinetics and lower water and energy consumption (Feng et al. 2021 ). Additionally, not only immobilized enzymes can be applied, but also the bacteria itself using bioreactors with a microbial consortium. The use of salt-tolerant bacteria can replace the conventional biological treatment, which may require an expensive and laborious desalination step (Tan et al. 2019 ). Halophilic microorganisms are also used for the bioremediation of saline-contaminated aquatic and terrestrial environments. Oil contamination poses a risk to all forms of life, including humans. In this context, microorganisms can be used to degrade contaminants. This process, besides being effective, is simple, economical, and does not cause significant environmental damage (Ghaedrahmat et al. 2022 ). However, most organisms currently used for this purpose do not withstand or degrade contaminants in high salt concentrations, highlighting the importance of studies on halophiles for bioremediation (Zhao et al. 2023 ). Besides industrial and environmental applications, salt-tolerant organisms are models for astrobiological studies. Mars contains elements necessary for the origin and maintenance of life, and there are evidence of the presence of liquid water on that planet. However, the presence of perchlorate salts on the surface and in subsurface brines may pose a challenge to life, since these compounds my damage microbial cells by inducing oxidative stress and biomolecules destabilization (Cockel, 2014; Heinz et al. 2021 ). Despite this, halophilic organisms have shown to resist to oxidative stress caused by perchlorate (Oren et al . 2013; Laye and DasSarma 2018 ). Some halophilic organisms have demonstrated the ability to survive at perchlorate concentrations higher than those found on Mars (0.4–0.6 wt %) (Flores et al. 2020 ; García-Descalzo et al. 2023 ). On icy moons like Enceladus and Europa, NaCl is the main salt present in varying concentrations in their saline oceans (Ashkenazy and Tziperman 2021 ; Trumbo et al. 2022 ; Weber et al. 2023 ). Both moons contain important elements for life and are geologically active (Kang et al., 2022 ; Weber et al., 2023 ). Halotolerant bacteria can be found in various places in Brazil, such as the mangroves, Araruama Lagoon in Rio de Janeiro, and the brines in Ceará and Rio Grande do Norte (Camara 2021 ; Cardoso et al. 2011 ; Duarte et al. 2012 ). Ceará state has historical significance in Brazil's salt economy. It attracted the Dutch garrison during the colonial period due to the presence of natural salt flats in the municipality of Camocim (Diniz and Vasconcelos, 2016 ). Although Brazil hosts numerous saline environments and salt-tolerant microorganisms hold significant potential for economic, environmental, and astrobiological applications, the Brazilian halotolerant microbiome remains largely underexplored. This study aimed to investigate halotolerant bacteria isolated from different areas of Camocim, Ceará, Brazil. We evaluated the environmental and industrial applications of the strains by analyzing their capacity to produce biosurfactants, grow using hydrocarbons as the sole carbon source, produce exopolysaccharides and the enzymes lipase, protease, and amylase. Additionally, we explored heir potential application in astrobiology studies by studying their tolerance to sodium perchlorate and the ability to use this salt as the sole electron acceptor. MATERIALS AND METHODS Isolation and maintenance of bacterial strains Strains were isolated from soils collected in Camocim, Ceará, Brazil in three distinct areas. These areas include the brine owned by the company Umari Salineira, at bare and rhizospheric soil, and the rhizospheric soil of the mangroove (2°55'59"S 40°49'50"W). Additionally, rhizospheric soil of herbaceous plants at Praia do Farol (2°51'43"S 40°51'44"W), and bare (2°52'33"S 40°55'48"W) and rhizospheric (2°52'36"S 40°55'24"W) soils of the dunes at Estrada para Maceió were also included (Fig. 1 ). The bare soil samples were collected at a depth of 0 to 5 centimeters. The isolation of halophilic and halotolerant bacteria was performed on a Tryptone Soy Agar (TSA) medium containing 100 g L − 1 and 50 g L − 1 NaCl, at 30°C and 50°C. The microorganisms were preserved by cryopreservation using glycerol at -80°C. The microorganisms were reactivated in Tryptic Soy Agar (TSA) and subsequently inoculated into Tryptic Soy Broth (TSB), both media prepared without the addition of NaCl prior to the subsequent experiments. Identification Strain identification was initially performed using the fatty acid methyl ester (FAME) analysis protocol recommended by MIDI Inc., based in Newark, Delaware, USA. FAMEs were analyzed using MIDI Sherlock® software with the TSB method and library. The organisms were further identified by 16S rRNA sequencing. The extraction of total DNA was carried out using the Biospin Bacteria Genomic DNA Extraction Kit by BioFlux according to the manufacturer's instructions. The amplification of the 16S rRNA coding sequence was done using universal primers for bacteria 27F (5’-AGAGTTTGATCMTGGCTCAG-3’) and 1492R (5’-TACGGYTACCTTGTTACGACTT-3’). The thermal cycling conditions included an initial denaturation at 95°C for 2 minutes, followed by 34 cycles of denaturation at 95°C for 2 minutes, annealing at 55°C for 30 seconds, and extension at 72°C for 60 seconds, with a final extension at 72°C for 5 minutes. Amplifications were carried out in a thermal cycler. The products resulting from the Polymerase Chain Reaction (PCR) were evaluated by agarose gel electrophoresis, with quantification done using Qubit® The PCR products were purified using the Ultraclean PCR purification kit according to the manufacturer's instructions and sequenced by Sanger method using an ABI sequencer. Sequence quality was assessed and automatically trimmed using Seqtk (v1.3). Nucleotide sequences were compared against the NCBI non-redundant database using BLASTn (v2.12.0+) with an e-value threshold of 1e-10. The resulting sequences were aligned using MUSCLE (v5.1). Poorly aligned regions were trimmed with TrimAl (v1.4.1) using the parameters -gt 0.8 (maximum gap fraction) and -cons 60 (minimum conservation score). Phylogenetic relationships were inferred using IQ-TREE (v2.2.0) under the Maximum Likelihood (ML) framework. The best-fit substitution model was selected automatically via ModelFinder (implemented in IQ-TREE). Branch support was assessed with ultrafast bootstrap approximation (UFBoot) using 1,000 replicates. Nodes with UFBoot support ≥ 95% were considered strongly supported. Sodium chloride and perchlorate tolerance Tolerance experiments to sodium chloride and perchlorate were conducted in 96-well microplates. The microorganisms were grown at 30°C in Tryptic Soy Broth (TSB) supplemented with 100, 150, and 200 g L − 1 NaCl, or with 10, 30, 50, 70, 90, and 110 g L − 1 NaClO 4 . The incubation was carried out in a BioTek microplate reader at 30°C for 72 hours, with growth measured by Optical Density at 600 nanometers (OD 600 ) every 30 minutes. Data were stored and analyzed using the Gen5 software. The evaluation of salt tolerance was performed by calculating the specific growth rate (µ) using the formula µ = ln 2 / G , where G represents the generation time. We compared the salt tolerance among the strains using ANOVA (Analysis of Variance) and Tukey's post-hoc test for the concentrations for the data that met ANOVA assumptions and the Kruskal-Wallis test followed by Dunn's post-hoc test for those that did not. Statistical analyses were made using the R software. Perchlorate reduction The ability of microorganisms to grow in an anoxic environment using perchlorate as the sole electron acceptor was analyzed by transferring 1 mL of a culture obtained in Anaerobic Lactate-Perchlorate Medium (ALP) to 15 mL penicillin vials containing Low-Mineral Medium (LMM), which was supplemented with 10 mM NaClO4 and purged with nitrogen (N 2 ) to eliminate oxygen (O 2 ) (Bruce et al. 1999 ; Wang et al. 2018 ). A control group was established by inoculating microorganisms into anaerobic LMM medium without perchlorate. After 14 days of incubation, bacterial growth was assessed by measuring dry biomass in the medium and by visual assessment using optical microscopy/simple staining. To assess cellular viability, we conducted an ATP assay utilizing a luciferase probe (Ludin, 2000). The culture was prepared in the previously mentioned LMM medium in a 96-well microplate, following incubation in an anaerobic chamber at 35°C. After 14-day, we used BacTiter-GloTM Microbial Cell Viability Assay to measure luciferase luminescence using a Thermo Scientific Varioskan Lux. Biosurfactant production and growth in hydrocarbon medium All microorganisms were tested for their ability to produce biosurfactants using the drop collapse technique described by A. Bodour and Miller-Maier (1998). Briefly, the inoculum was prepared in TSB medium and then incubated at 30°C and 200 rpm for 24 or 48 hours, depending on the bacterium growth rate. Bacteria that showed positive results in the initial test had the surface tension of the growth medium measured using a Dataphysics tensiometer and the DCATS 31 software to confirm the reduction in surface tension. To assess the growth of the strains using hydrocarbons as the sole carbon source, the strains were grown in MSM medium with 2% (v/v) hexadecane for 15 days. After this time, resazurin was added as an activity indicator (active cells reduce resazurin to resorufin, a pink compound). Synthesis of exopolysaccharides We assessed synthesis of exopolysaccharide by streaking the strains on Luria-Bertani Agar (LBA) containing 0.2 g L − 1 Calcofluor. Fluorescent colonies under UV-C light exposure were considered positive for exopolysaccharide production (Leigh et al., 1985 ). Enzymatic production Enzyme production was assessed in 0.1X LBA medium with 10 g L − 1 temperature and at 50°C for the others, at 200 rpm for 24 or 48 hours, depending on the strain. The OD 600 were determined and normalized to 0.1, and 10 µL of the culture was spotted onto plates containing the enzyme substrates. The plates were then incubated at 30°C or 50°C. The presence of the enzymes was determined by the appearance of clear zones around the culture. RESULTS AND DISCUSSION Identification Fatty acids analysis did not provide clear identification at the species level, except for CaSRM9, identified as Bacillus licheniformis (SIM index > 0.8). The SIM index was between 0.6 and 0.8 for five strains identified as Bacillus , which agreed with the phylogenetic analysis using rRNA 16s. The phylogenetic analysis suggests that most strains belong to the Bacillus genus clade (Gupta et al. 2020; Spring et al. 1996). The predominance of Bacillus among strains isolated from saline medium aligns with previous studies that frequently report halotolerant Bacillus worldwide (Nas et al. 2021; Nimkande et al. 2023; Orhan and Gulluce 2015; Reang et al. 2024). Table 1 presents the strains along with their classification based on fatty acid composition as well as their respective isolation sites. Figure 2 illustrates the phylogenetic relationships among the strains and closely related species. Sodium chloride tolerance All 20 tested strains were able to withstand 100 g L − 1 NaCl, with CaSRM5 showing the highest mean specific growth rate at this salt concentration (µ = 0.326 h − 1 ). Eleven strains were able to grow at 150 g L − 1 , with CaSDR7 reaching the highest specific growth rate at this salt concentration (µ = 0.241 h − 1 ). This strain did not perform as well at the lower salt concentration (µ = 0.125 h − 1 ). Only CaSS7 was able to grow at 200 g L − 1 , albeit very slowly (µ = 0.0164 h − 1 ). Despite being able to withstand higher concentrations of NaCl, CaSS7 presented lower µ values at lower salt concentrations compared to the other strains (µ = 0.060 h − 1 at 100 g L − 1 and 0.032 at 150 g L − 1 ). These results indicate no direct relation between the growth rate in the presence of NaCl and tolerance to higher concentrations of this salt. ANOVA assumptions were not met by the µ values at 100 and 150 g L − 1 . Therefore, we analyzed the data using the Kruskal-Wallis test and Dunn test, which showed significant differences among the strains. Using the suggested classification of Larsen (1986), the strains obtained in this study were classified as moderate halotolerant (organisms which withstand up to 180 or 200 g L − 1 NaCl) (Table 2). Table 1 Identification of Strains Using FAME (MIDI Sherlock), Including Isolation Sites and Similarity Indices. Strain Site ID FAME (SIM index) CaSDR1 Dune rhizospheric soil Bacillus megaterium (0.593) CaSDR7 Dune rhizospheric soil Pseudomonas oryzihabitans ( 0.282) CaSDA4 Dune bare soil Brevibacillus formosus (0.319) CaPFR3 Praia do Farol rhizospheric soil Bacillus subtilis (0.693) CaPFR7 Praia do Farol rhizospheric soil Paenibacillus macerans (0.414) CaSRS1 Brine rhizospheric soil - CaSRS4 Brine rhizospheric soil Bacillus alcalophilus (0.366) CaSRS8 Brine rhizospheric soil - CaSRS10 Brine rhizospheric soil Bacillus pumilus (0.642) CaSS7 Brine bare soil - CaSS10 Brine bare soil Bacillus pumilus (0.621) CaSRM1 Mangrove rhizospheric soil Bacillus atrophaeus (0.696) CaSRM5 Mangrove rhizospheric soil Bacillus sp . (0.209) CaSRM7 Mangrove rhizospheric soil - CaSRM8 Mangrove rhizospheric soil Bacillus sp . (0.406) CaSRM9 Mangrove rhizospheric soil Bacillus licheniformis (0.812) CaSRM12 Mangrove rhizospheric soil - CaSRM15 Mangrove rhizospheric soil Microbacterium barkeri (0.575) CaSRM16 Mangrove rhizospheric soil Bacillus subtilis (0.627) CaSRM18 Mangrove rhizospheric soil Halomonas aquamarina (0.425) *A similarity index (SIM index) 0.8 indicates high similarity. Five strains did not match any entries in the MIDI Sherlock TSB library. Table 2 - Specific growth rates (μ) of the bacterial strains at 100 g L -1 and 150 g L -1 NaCl. Strains labeled with different letters indicate significant differences of their respective specific growth rates at the same concentration of NaCl (p ≤ 0.05). Bacterial Strain ----------------------------- NaCl concentration ----------------------------- 100 g L -1 150 g L -1 Mean μ Median μ Mean μ Median μ CaDA4 0.1812 0.179 abc 0.124 0.126 ab CaDR1 0.137 0.137 abc - - CaDR7 0.125 0.125 abc 0.241 0.241 a CaPFR3 0.159 0.166 abc - - CaPFR7 0.233 0.233 a - - CaSRM1 0.113 0.115 abc 0.102 0.095 ab CaSRM12 0.074 0.071 bc - - CaSRM15 0.145 0.147 abc - - CaSRM16 0.182 0.183 abc 0.168 0.168 a CaSRM18 0.147 0.147 abc 0.048 0.049 bc CaSRM5 0.326 0.323 a - - CaSRM7 0.137 0.119 abc - - CaSRM8 0.165 0.165 abc 0.026 0.034 c CaSRM9 0.277 0.275 ab 0.100 0.102 ab CaSRS1 0.080 0.080 abc 0.053 0.054 bc CaSRS10 0.128 0.160 abc - - CaSRS4 0.179 0.175 abc - - CaSRS8 0.051 0.051 c 0.068 0.061 bc CaSS10 0.076 0.074 bc 0.016 0.016 c CaSS7 0.060 0.063 c 0.032 0.032 c Sodium perchlorate tolerance The µ values obtained during the perchlorate tolerance experiment did not meet ANOVA assumptions at concentrations of 10 to 90 g L − 1 (Tables 3 and 4). As a result, we used the Kruskal-Wallis test and the Dunn test. However, at 110 g L − 1 , we performed ANOVA and the Tukey test (Table 5). Table 3 Specific growth rates (μ) of the bacterial strains in medium containing NaClO₄. Strains labeled with different letters indicate significant differences at the same concentration of NaClO₄ (p ≤ 0.05). Bacterial strain ----------------------------- NaClO₄ concentration ----------------------------- 10 g L -1 30 g L -1 50 g L -1 Mean μ Median μ Mean μ Median μ Mean μ Median μ CaDA4 0.171 0.169 ghi* 0.147 0.162 efg - - CaDR1 0.156 0.167 ghi 0.171 0.169 cdefg 0.186 0.184 bcdefg CaDR7 0.095 0.099 i 0.170 0.171 cdefg 0.145 0.147 cdefgh CaPFR3 0.226 0.213 defg 0.162 0.160 defg 0.117 0.112 efgh CaPFR7 0.158 0.156 ghi 0.120 0.118 g 0.226 0.225 abcde CaSRM1 0.389 0.377 abcd 0.534 0.546 a 0.328 0.389 abc CaSRM12 0.217 0.225 fgh 0.189 0.182 cdefg 0.081 0.073 gh CaSRM15 0.347 0.343 abcdef 0.178 0.174 cdefg 0.219 0.227 abcde CaSRM16 0.358 0.354 abcdef 0.231 0.224 abc 0.266 0.252 ab CaSRM18 0.429 0.443 abc 0.518 0.522 a 0.351 0.396 ab CaSRM5 0.114 0.114 hi 0.185 0.185 bcdef 0.134 0.126 defgh CaSRM7 0.251 0.262 cdefg 0.224 0.238 abcd 0.094 0.082 fgh CaSRM8 0.451 0.444 ab 0.325 0.331 ab 0.259 0.251 abc CaSRM9 0.237 0.229 defg 0.174 0.173 cdefg 0.144 0.138 cdefgh CaSRS1 0.212 0.213 efgh 0.213 0.220 abcde 0.042625 0.050 h CaSRS10 0.374 0.371 abcde 0.263 0.276 abc 0.240825 0.213 abcde CaSRS4 0.243 0.222 efgh 0.233 0.234 abcde 0.235625 0.244 abcd CaSRS8 0.260 0.254 bcdefg 0.140 0.152 fg 0.209900 0.206 abcdef CaSS10 0.560 0.537 a 0.471 0.455 a 0.576775 0.574 a CaSS7 0.187 0.177 ghi 0.186 0.195 bcdefg 0.042800 0.042 h Table 4 Specific growth rates (μ) of the bacterial strains in medium containing 70 110 g L -1 NaClO₄. Strains labeled with different letters indicate significant differences at the same NaClO₄ concentration. For concentrations of 70 and 90 g L -1 NaClO₄ we performed Kruskal-Wallis and the Dunn statistical test and for 110 g L -1 NaClO₄ we performed ANOVA and Tukey test (p ≤ 0.05). Bacterial strain ----------------------------- NaClO₄ concentration ----------------------------- 70 g L -1 90 g L -1 110 g L -1 Mean μ Median μ Mean μ Median μ Mean μ Median μ CaDR1 0.545 0.536 a* 0.122 0.107 efgh - - CaDR7 0.240 0.230 cdef 0.161 0.160 bcd - - CaPFR3 0.152 0.150 fghi 0.131 0.125 defgh 0.152 ab 0.162 CaPFR7 0.313 0.320 abc 0.303 0.286 ab - - CaSRM1 0.077 0.082 ghi - - - - CaSRM12 0.287 0.291 bcde 0.227 0.230 abcd 0.105 b 0.124 CaSRM15 0.317 0.306 abcd 0.203 0.206 abcde 0.259 a 0.245 CaSRM16 0.381 0.366 ab 0.245 0.248 abc 0.140 ab 0.147 CaSRM18 0.175 0.175 defg 0.190 0.175 bcd 0.176 ab 0.223 CaSRM5 0.164 0.155 efgh 0.290 0.29150 a 0.104 b 0.096 CaSRM7 0.138 0.137 fghi 0.058 0.04885 gh 0.151 ab 0.131 CaSRM8 0.155 0.155 fghi 0.183 0.18350 bc 0.152 ab 0.154 CaSRM9 0.356 0.316 abc 0.272 0.27350 ab 0.094 b 0.086 CaSRS1 0.034 0.033 hi 0.023 0.02255 h 0.055 b 0.042 CaSRS10 0.298 0.288 bcd 0.193 0.18595 bc 0.095 b 0.097 CaSRS4 0.379 0.380 ab 0.237 0.23720 abc 0.138 ab 0.127 CaSRS8 0.096 0.101 ghi 0.039 0.03830 h 0.066 b 0.067 CaSS10 0.289 0.282 bcde 0.222 0.22065 abcd - - CaSS7 0.027 0.028 i 0.082 0.08610 fgh 0.137 ab 0.132 Table 5 Biosurfactant Production by the halotolerant bacterial strains. Surface tension was measured only for bacteria that showed positive results in the drop collapse test. Additionally, growth in MSM medium containing hexadecane as the sole carbon source was assessed. Strain Drop collapse Surface tension Growth on hydrocarbon CaSDR1 - NE + CaSDR7 - NE + CaSDA4 - NE - CaPFR3 + 29.187 +/- 0.025 - CaPFR7 + 30.350 +/- 0.023 - CaSRS1 - NE - CaSRS4 - NE - CaSRS8 - NE - CaSRS10 - NE + CaSS7 - NE - CaSS10 - NE - CaSRM1 - NE - CaSRM5 + 29.511 +/- 0.029 - CaSRM7 - NE - CaSRM8 + 45.910 +/- 0.029 - CaSRM9 - NE - CaSRM12 - NE - CaSRM15 - NE + CaSRM16 - NE - CaSRM18 + 27.716 +/- 0.018 + *NE = Not Evaluated Table 6 Production of amylases, lipases and proteases by the strains. Strain amylases lipases proteases CaDR1 - + + CaDR7 - + + CaSDA4 - - + CaPFR3 + + - CaPFR7 - + + CaSRM1 + - + CaSRM5 + + + CaSRM7 - + + CaSRM8 + - - CaSRM9 - + + CaSRM12 - + + CaSRM15 - + + CaSRM16 + + + CaSRM18 - + - CaSRS1 + + - CaSRS4 - + + CaSRS8 - - + CaSRS10 - + + CaSS7 - + - CaSS10 - + - CaSDA4 showed a high µ at NaCl concentrations of 100 and 150 g L − 1 , but could not tolerate more than 30 g L − 1 NaClO₄. This aligns with previous studies that reported a higher tolerance to chloride compared to perchlorate salts (Flores et al. 2020; Heinz et al. 2019). CaSS10 and CaSRM18 exhibited higher growth rates at 10, 30, 50, and 110 g L − 1 NaClO₄ compared to other strains, but did not perform as well in the NaCl tolerance experiment. This indicates that there is no direct relationship between tolerance to NaCl and NaClO₄. Perchlorate is likely hazardous due to its chaotropic and oxidative nature, while NaCl induces osmotic stress (Heinz et al. 2021; Saini et al. 2023). Therefore, the lack of correlation between the µ values observed in the two experiments may reflect differences in the degree of destabilization caused by these two stressors and in the mechanisms of cell damage caused by each of them. Perchlorate reduction During anaerobic growth on NaClO₄ as electron acceptor, the bacterial strains CaSRS1, CaSRS8, CaSRM5, CaSRM7, CaSRM12, and CaSRM16 formed cell aggregates that could not be disrupted even with intense vortexing (Fig. 3). Microscopic aggregates were also observed for the other strains (Fig. 4). This agrees with previous studies that reported aggregate formation as a response to perchlorate toxicity (Heinz et al., 2019). With the exceptions of CaSS7 and CaSRM7, all microorganisms produced detectable biomass (Fig. 5A). Among these, CaDR1 exhibited the highest biomass, and CaDR1 and CaDR7 demonstrated the highest luciferase luminescence in the ATP assay. This assay indicated that all strains showed luciferase luminescence, demonstrating their viability in a medium where perchlorate served as the sole electron acceptor (Fig. 5B). The ability to not only tolerate perchlorate but also utilize it for respiration is particularly significant in astrobiology, especially in the context of an anoxic Mars with brines rich in perchlorate salts. These organisms could serve as models for studying Mars's habitability and raise concerns about interplanetary contamination. Their capacity to withstand and respire perchlorate makes them potential contaminants of Mars. Furthermore, Bacillus species can form endospores, enhancing their resilience to conditions found on Mars and in spacecraft (Mettler et al., 2023). Biosurfactant production and growth on hydrocarbon In the drop collapse test, CaPFR3, CaPFR7, CaSRM5, CaSRM8, and CaSRM18 showed positive results and were further tested for reduction of surface tension in TSB medium (Table 5). The surface tension of the growth medium was 72. All the above isolates could reduce the surface tension of the medium. The lowest surface tension was obtained in the medium inoculated with CaSRM18 (27.716 +/- 0.018). This biosurfactant producing bacterium was the only able to growth in MSM medium containing hydrocarbon as the sole carbon source (see below). Other bacteria capable of growing using hydrocarbon as the sole carbon source (CaSDR1, CaSDR7, CaSRS10, and CaSRM15) did not produce biosurfactant in the tested conditions. Halotolerant Bacillus are known for producing biosurfactants. For example, a marine Bacillus licheniformis could reduce surface tension of the growth medium by 31.4% and degrade engine oil (Nayak et al. 2020). Accordingly, Bacillus halotolerans , isolated from metal-contaminated soil, produces biosurfactants with potential antioxidant, antimicrobial, and anticancer properties (Etemadzadeh et al . 2024). Biosurfactants have various applications beyond the oil industry, including use in detergents, food, cosmetics, pharmaceuticals, agriculture, and nanotechnology (Sarubbo et al. 2022). Therefore, even strains that cannot use hexadecane or other hydrocarbons as the sole carbon source can be a source of biosurfactants for a variety of applications. Synthesis of exopolysaccharides Sixteen among the 20 bacterial strains showed positive results for exopolysaccharide synthesis (Fig. 6). The production of exopolysaccharide (EPS) aligns with the observations of aggregate formation during perchlorate reduction experiments, as these polymers play a crucial role in cellular aggregation and adherence. Halophilic and halotolerant bacteria synthesize exopolysaccharides (EPS) as a survival mechanism when exposed to harsh conditions. These polymers can exhibit biosurfactant properties and, therefore, contribute to bioremediation (Ibrahim et al., 2020). In addition to bioremediation, EPS also finds applications in the food, pharmaceutical, and agricultural industries. Moreover, EPS is utilized in waste treatment due to its metal chelation, flocculation, and colloid formation properties. Research has shown that EPS produced by Bacillus spp. isolated from mangrove ecosystems demonstrated antimicrobial, cytotoxic, antioxidant, and anti-inflammatory activities, highlighting the importance of studying EPS-producing strains from these and other underexplored ecosystems (Díaz-Cornejo et al., 2023). Additionally, exopolysaccharides produced by this genus were capable of inhibiting biofilm formation by Staphylococcus aureus , a pathogen associated with bovine mastitis in veterinary medicine (Sabino et al. 2023). Enzymatic production All the bacterial isolates produced at least one of the three enzymes evaluated (Table 6). Lipase and protease were produced more frequently (16 and 14 out of 20 bacterial isolates, respectively). In contrast, only 6 isolates produced amylase. Notably, CaSRM5 and CaSRM16 produced all three enzymes, while five isolates produced just one enzyme: CaSDA4 and CaSRS8 produced proteases; CaSRM8 produced amylases; and CaSRM18, CaSS7, and CaSS10 produced lipases. The production of hydrolases by salt-tolerant bacteria was reported by Drissi Kaitouni et al. (2020), who isolated bacteria from a salt mine and two salt marshes. From 227 bacteria collected, they found that 189 synthesized hydrolases, including amylases and proteases. Additionally, Fatholahpoor et al. (2020) isolated salt-tolerant bacteria from the Eshtehard Desert in Iran, and reported that out of 32 strains, 18 exhibited lipase activity, 12 showed protease activity, and 11 had amylase activity. These enzymes, aside from their role in wastewater treatment, have applications in various industries, such as food, pharmaceuticals, and detergents, among others (Mesbah 2022; Mokasheet al. 2018; Qiu et al. 2021). CONCLUSION Brazil possesses significant potential for a vast microbial biodiversity with various applications. Our study focused on the biotechnological and astrobiological applications of halotolerant bacteria isolated from different habitats in a microbiologically underexplored region (Camocim, CE). These microorganisms can tolerate high concentrations of NaCl and perchlorate, a toxic salt commonly found on Mars. Moreover, they can utilize sodium perchlorate as a sole electron acceptor in anaerobic conditions, making them excellent astrobiological models and candidates for survival experiments under simulated anoxic Martian environments. In terms of biotechnological applications, five of the 20 microorganisms produced biosurfactants, while 16 produced exopolysaccharides, both of which have numerous industrial and biotechnological applications. Additionally, these microorganisms produce the enzymes lipases, proteases, and amylases, which are applicable in various industrial sectors. This study highlights the importance of improving prospection efforts to unravel the microbial diversity, particularly of extremophiles, and lays the groundwork for future research. Upcoming studies should focus on using omics technologies to better understand the mechanisms behind perchlorate tolerance and reduction by these organisms, as well as assess their specific industrial applications. Declarations Conflict of Interest Statement The authors declare no conflicts of interest related to this work. References Ali N, Nughman M, Shah SM. Extremophiles and limits of life in a cosmic perspective. In: Najjari A, editor. Life in extreme environments: diversity, adaptability and valuable resources of bioactive molecules. London: IntechOpen; 2023. https://doi.org/10.5772/intechopen.110471. Ashkenazy Y, Tziperman E. Dynamic Europa ocean shows transient Taylor columns and convection driven by ice melting and salinity. Nat Commun. 2021;12:6376. https://doi.org/10.1038/s41467-021-26710-0. 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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-6958968","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":475331779,"identity":"4bc1eb31-24ef-4c4d-8900-ac3c7ea953de","order_by":0,"name":"Camila Souza Vieira","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA7UlEQVRIie3QsYoCMRCA4ZHAbrO4bSp9hRzXir7KBAurBa9WOBchdtrqWyzYWowIsdAHsFM5sBO0OayOGwVhG5PWIn+TTfFlhgUIhd40OjyOygAQoAaCQHgJlsgnROgngKVvPfCRdLTRhH1ogWznh+Oi2SlsosTX4jWR26wgtPy41EOFp3b2INPTa6LgTiLeLVkaiSSyYm9QJOQg6ZnJHy+WLEc3pO+OspGHSJ6iDf+uODeAtEJlBTmJ3PEUPZbaxPmQF1t/zJispg6STrL55fLbaKUiPl5v1KtXbSX/6TrIcxhE5asfhEKhUMjZP6RsVPswOlNtAAAAAElFTkSuQmCC","orcid":"","institution":"Federal University of Viçosa","correspondingAuthor":true,"prefix":"","firstName":"Camila","middleName":"Souza","lastName":"Vieira","suffix":""},{"id":475331780,"identity":"b8dd67ef-009c-43c9-b7a5-f16d6e4750c8","order_by":1,"name":"Jomar Lima Barros","email":"","orcid":"","institution":"Federal University of Viçosa","correspondingAuthor":false,"prefix":"","firstName":"Jomar","middleName":"Lima","lastName":"Barros","suffix":""},{"id":475331781,"identity":"af5a7e2a-d8b4-4389-8491-f3554d0df2b0","order_by":2,"name":"Caio Issamu Somiza","email":"","orcid":"","institution":"Federal University of Viçosa","correspondingAuthor":false,"prefix":"","firstName":"Caio","middleName":"Issamu","lastName":"Somiza","suffix":""},{"id":475331782,"identity":"b99462a0-e954-4bcf-90b9-9ededb38cc9e","order_by":3,"name":"Edmo Montes Rodrigues","email":"","orcid":"","institution":"Instituto Federal do Ceará","correspondingAuthor":false,"prefix":"","firstName":"Edmo","middleName":"Montes","lastName":"Rodrigues","suffix":""},{"id":475331783,"identity":"538dd94b-0d0b-4c2b-8087-d66240364002","order_by":4,"name":"Marcos Rogério Tótola","email":"","orcid":"","institution":"Federal University of Viçosa","correspondingAuthor":false,"prefix":"","firstName":"Marcos","middleName":"Rogério","lastName":"Tótola","suffix":""}],"badges":[],"createdAt":"2025-06-23 17:23:24","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6958968/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6958968/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":85292651,"identity":"08d27abc-56f5-4621-87f2-271c15f32c6a","added_by":"auto","created_at":"2025-06-24 10:18:01","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":561779,"visible":true,"origin":"","legend":"\u003cp\u003eMap of the collection areas. Collections sites are represented with red dots. A = brine area (2°55'59\"S 40°49'50\"W), B = Praia do Farol (2°51'43\"S 40°51'44\"W), C = Dunes (bare: 2°52'33\"S 40°55'48\"W and rhizospheric: 2°52'36\"S 40°55'24\"W).\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-6958968/v1/871169e41bdc0717c30e2b04.png"},{"id":85292283,"identity":"e02a9e01-073f-4fef-9e93-9a8daf2435b8","added_by":"auto","created_at":"2025-06-24 10:10:01","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":679678,"visible":true,"origin":"","legend":"\u003cp\u003ePhylogenetic tree illustrating the relationships among the strains and closely related species.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-6958968/v1/a0564c40b7e7cd7d069910d4.png"},{"id":85292281,"identity":"cb82d3ef-17fb-48d7-b3c0-7fba2df3874c","added_by":"auto","created_at":"2025-06-24 10:10:01","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":342994,"visible":true,"origin":"","legend":"\u003cp\u003eCell aggregates formed by CaSRS1, CaSRS8, CaSRM5, CaSRM7, CaSRM9, CaSRM12, and CaSRM16 during anaerobic growth using perchlorate as sole electrons acceptor.\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-6958968/v1/3ce3a5cbae5aaeb7e442fddc.png"},{"id":85292284,"identity":"aa7f29de-9491-4c24-8c2c-cfc6e76958f5","added_by":"auto","created_at":"2025-06-24 10:10:01","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":877320,"visible":true,"origin":"","legend":"\u003cp\u003eMicroscopic visualization of the bacterial strains after 14 days in anaerobic medium with sodium perchlorate as sole electrons acceptor. CaDR1, CaDR7, CaSDA4, CaPFR3, CaPFR7, CaSS7, CaSS10, CaSRS1, CaSRS4, CaSRS8, CaSRS10, CaSRM1, CaSRM5, CaSRM7, CaSRM8, CaSRM9, CaSRM12, CaSRM15, and CaSRM18 (A, B, C, D, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, and T respectively).\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-6958968/v1/ee208a966e49f178e1a30e04.png"},{"id":85292652,"identity":"54308922-044a-4929-a2ab-296160b1c983","added_by":"auto","created_at":"2025-06-24 10:18:02","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":552886,"visible":true,"origin":"","legend":"\u003cp\u003eGrowth and ATP-derived luminescence of the bacterial strains in medium with perchlorate as sole electrons acceptor. (A): dry biomass of the strains in 15 mL of medium after 14 days of incubation; B: ATP assay using luciferin/luciferase probe.\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-6958968/v1/8395bfb8cd440c29841f11e1.png"},{"id":85292286,"identity":"19068fd3-75ca-4c1a-b961-f22e6b5a7db5","added_by":"auto","created_at":"2025-06-24 10:10:02","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":373715,"visible":true,"origin":"","legend":"\u003cp\u003eExopolysaccharide synthesis by the halotolerant bacterial strains. Fluorescence emission upon exposure to UV-C light indicates positive result.\u003c/p\u003e","description":"","filename":"floatimage9.png","url":"https://assets-eu.researchsquare.com/files/rs-6958968/v1/493a93050741f0a13ffde033.png"},{"id":87301189,"identity":"ceff3d3d-6fb6-4ec6-8b29-386bfc9b8eb0","added_by":"auto","created_at":"2025-07-22 13:23:29","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4545791,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6958968/v1/994eaedf-0104-490e-b3e7-95522b371b55.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eHalotolerant Bacteria From Camocim, Brazil: Prospects for Astrobiology and Biotechnology\u003c/p\u003e","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eThe study of extremophiles has gained significant attention in recent years due to their diverse scientific and biotechnological applications, which result from their remarkable adaptations to harsh environments. Extremophiles can be classified into various categories based on the extreme conditions they are capable of withstanding. These categories include thermophiles, hyperthermophiles, psychrophiles, psychrotolerants, acidophiles, alkaliphiles, barophiles, halophiles, and halotolerants (Ali et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eHalotolerant bacteria are different from halophiles in that they do not require NaCl to live, but can withstand high concentrations of this salt (Larsen \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e1986\u003c/span\u003e). Non halophiles/non halotolerants are affected by high NaCl concentrations, losing cellular water by osmosis, but salt-tolerant microorganisms have adaptive mechanisms that allow them to survive under these extreme conditions (Mukhtar et al. \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). The salt-in mechanism maintains the ionic concentration in the cell through ions symport, antiport, and active transport (Gunde-Cimerman et al. \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). In contrast, the salt-out mechanism maintains the osmotic pressure through the synthesis or uptake of compatible solutes such as glycine betaine and trehalose (Ionescu et al. 2024).\u003c/p\u003e \u003cp\u003eAnother characteristic adaptation of halophiles is the higher number of acidic amino acids in their enzymes, compared to non-halophiles (Madern et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e1995\u003c/span\u003e). These adapted enzymes have applications in various industry sectors. They can maintain activity not only at high salt concentrations but also at extreme pH levels and temperatures (Delgado-Garc\u0026iacute;a et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). Halophilic enzymes can be used to treat saline wastewater. Lipases, amylases, and proteases have been studied for treating wastewater from the leather industry. This type of wastewater is rich in NaCl and mainly consists of lipids, mucopolysaccharides, and proteins (Maharaja et al. \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Enzymatic wastewater treatment is more effective than chemical treatment due to faster reaction kinetics and lower water and energy consumption (Feng et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Additionally, not only immobilized enzymes can be applied, but also the bacteria itself using bioreactors with a microbial consortium. The use of salt-tolerant bacteria can replace the conventional biological treatment, which may require an expensive and laborious desalination step (Tan et al. \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eHalophilic microorganisms are also used for the bioremediation of saline-contaminated aquatic and terrestrial environments. Oil contamination poses a risk to all forms of life, including humans. In this context, microorganisms can be used to degrade contaminants. This process, besides being effective, is simple, economical, and does not cause significant environmental damage (Ghaedrahmat et al. \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). However, most organisms currently used for this purpose do not withstand or degrade contaminants in high salt concentrations, highlighting the importance of studies on halophiles for bioremediation (Zhao et al. \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eBesides industrial and environmental applications, salt-tolerant organisms are models for astrobiological studies. Mars contains elements necessary for the origin and maintenance of life, and there are evidence of the presence of liquid water on that planet. However, the presence of perchlorate salts on the surface and in subsurface brines may pose a challenge to life, since these compounds my damage microbial cells by inducing oxidative stress and biomolecules destabilization (Cockel, 2014; Heinz et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Despite this, halophilic organisms have shown to resist to oxidative stress caused by perchlorate (Oren \u003cem\u003eet al\u003c/em\u003e. 2013; Laye and DasSarma \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Some halophilic organisms have demonstrated the ability to survive at perchlorate concentrations higher than those found on Mars (0.4\u0026ndash;0.6 wt %) (Flores et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Garc\u0026iacute;a-Descalzo et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). On icy moons like Enceladus and Europa, NaCl is the main salt present in varying concentrations in their saline oceans (Ashkenazy and Tziperman \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Trumbo et al. \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Weber et al. \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Both moons contain important elements for life and are geologically active (Kang et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Weber et al., \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eHalotolerant bacteria can be found in various places in Brazil, such as the mangroves, Araruama Lagoon in Rio de Janeiro, and the brines in Cear\u0026aacute; and Rio Grande do Norte (Camara \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Cardoso et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Duarte et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). Cear\u0026aacute; state has historical significance in Brazil's salt economy. It attracted the Dutch garrison during the colonial period due to the presence of natural salt flats in the municipality of Camocim (Diniz and Vasconcelos, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). Although Brazil hosts numerous saline environments and salt-tolerant microorganisms hold significant potential for economic, environmental, and astrobiological applications, the Brazilian halotolerant microbiome remains largely underexplored.\u003c/p\u003e \u003cp\u003eThis study aimed to investigate halotolerant bacteria isolated from different areas of Camocim, Cear\u0026aacute;, Brazil. We evaluated the environmental and industrial applications of the strains by analyzing their capacity to produce biosurfactants, grow using hydrocarbons as the sole carbon source, produce exopolysaccharides and the enzymes lipase, protease, and amylase. Additionally, we explored heir potential application in astrobiology studies by studying their tolerance to sodium perchlorate and the ability to use this salt as the sole electron acceptor.\u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eIsolation and maintenance of bacterial strains\u003c/h2\u003e \u003cp\u003eStrains were isolated from soils collected in Camocim, Cear\u0026aacute;, Brazil in three distinct areas. These areas include the brine owned by the company Umari Salineira, at bare and rhizospheric soil, and the rhizospheric soil of the mangroove (2\u0026deg;55'59\"S 40\u0026deg;49'50\"W). Additionally, rhizospheric soil of herbaceous plants at Praia do Farol (2\u0026deg;51'43\"S 40\u0026deg;51'44\"W), and bare (2\u0026deg;52'33\"S 40\u0026deg;55'48\"W) and rhizospheric (2\u0026deg;52'36\"S 40\u0026deg;55'24\"W) soils of the dunes at Estrada para Macei\u0026oacute; were also included (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The bare soil samples were collected at a depth of 0 to 5 centimeters. The isolation of halophilic and halotolerant bacteria was performed on a Tryptone Soy Agar (TSA) medium containing 100 g L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 50 g L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e NaCl, at 30\u0026deg;C and 50\u0026deg;C. The microorganisms were preserved by cryopreservation using glycerol at -80\u0026deg;C. The microorganisms were reactivated in Tryptic Soy Agar (TSA) and subsequently inoculated into Tryptic Soy Broth (TSB), both media prepared without the addition of NaCl prior to the subsequent experiments.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eIdentification\u003c/h3\u003e\n\u003cp\u003eStrain identification was initially performed using the fatty acid methyl ester (FAME) analysis protocol recommended by MIDI Inc., based in Newark, Delaware, USA. FAMEs were analyzed using MIDI Sherlock\u0026reg; software with the TSB method and library. The organisms were further identified by 16S rRNA sequencing. The extraction of total DNA was carried out using the Biospin Bacteria Genomic DNA Extraction Kit by BioFlux according to the manufacturer's instructions. The amplification of the 16S rRNA coding sequence was done using universal primers for bacteria 27F (5\u0026rsquo;-AGAGTTTGATCMTGGCTCAG-3\u0026rsquo;) and 1492R (5\u0026rsquo;-TACGGYTACCTTGTTACGACTT-3\u0026rsquo;). The thermal cycling conditions included an initial denaturation at 95\u0026deg;C for 2 minutes, followed by 34 cycles of denaturation at 95\u0026deg;C for 2 minutes, annealing at 55\u0026deg;C for 30 seconds, and extension at 72\u0026deg;C for 60 seconds, with a final extension at 72\u0026deg;C for 5 minutes. Amplifications were carried out in a thermal cycler. The products resulting from the Polymerase Chain Reaction (PCR) were evaluated by agarose gel electrophoresis, with quantification done using Qubit\u0026reg; The PCR products were purified using the Ultraclean PCR purification kit according to the manufacturer's instructions and sequenced by Sanger method using an ABI sequencer. Sequence quality was assessed and automatically trimmed using Seqtk (v1.3). Nucleotide sequences were compared against the NCBI non-redundant database using BLASTn (v2.12.0+) with an e-value threshold of 1e-10. The resulting sequences were aligned using MUSCLE (v5.1). Poorly aligned regions were trimmed with TrimAl (v1.4.1) using the parameters -gt 0.8 (maximum gap fraction) and -cons 60 (minimum conservation score). Phylogenetic relationships were inferred using IQ-TREE (v2.2.0) under the Maximum Likelihood (ML) framework. The best-fit substitution model was selected automatically via ModelFinder (implemented in IQ-TREE). Branch support was assessed with ultrafast bootstrap approximation (UFBoot) using 1,000 replicates. Nodes with UFBoot support\u0026thinsp;\u0026ge;\u0026thinsp;95% were considered strongly supported.\u003c/p\u003e\n\u003ch3\u003eSodium chloride and perchlorate tolerance\u003c/h3\u003e\n\u003cp\u003eTolerance experiments to sodium chloride and perchlorate were conducted in 96-well microplates. The microorganisms were grown at 30\u0026deg;C in Tryptic Soy Broth (TSB) supplemented with 100, 150, and 200 g L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e NaCl, or with 10, 30, 50, 70, 90, and 110 g L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e NaClO\u003csub\u003e4\u003c/sub\u003e. The incubation was carried out in a BioTek microplate reader at 30\u0026deg;C for 72 hours, with growth measured by Optical Density at 600 nanometers (OD\u003csub\u003e600\u003c/sub\u003e) every 30 minutes. Data were stored and analyzed using the Gen5 software. The evaluation of salt tolerance was performed by calculating the specific growth rate (\u0026micro;) using the formula \u0026micro;\u0026thinsp;=\u0026thinsp;ln\u003csub\u003e2\u003c/sub\u003e/\u003cem\u003eG\u003c/em\u003e, where \u003cem\u003eG\u003c/em\u003e represents the generation time. We compared the salt tolerance among the strains using ANOVA (Analysis of Variance) and Tukey's post-hoc test for the concentrations for the data that met ANOVA assumptions and the Kruskal-Wallis test followed by Dunn's post-hoc test for those that did not. Statistical analyses were made using the R software.\u003c/p\u003e\n\u003ch3\u003ePerchlorate reduction\u003c/h3\u003e\n\u003cp\u003eThe ability of microorganisms to grow in an anoxic environment using perchlorate as the sole electron acceptor was analyzed by transferring 1 mL of a culture obtained in Anaerobic Lactate-Perchlorate Medium (ALP) to 15 mL penicillin vials containing Low-Mineral Medium (LMM), which was supplemented with 10 mM NaClO4 and purged with nitrogen (N\u003csub\u003e2\u003c/sub\u003e) to eliminate oxygen (O\u003csub\u003e2\u003c/sub\u003e) (Bruce et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e1999\u003c/span\u003e; Wang et al. \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). A control group was established by inoculating microorganisms into anaerobic LMM medium without perchlorate. After 14 days of incubation, bacterial growth was assessed by measuring dry biomass in the medium and by visual assessment using optical microscopy/simple staining. To assess cellular viability, we conducted an ATP assay utilizing a luciferase probe (Ludin, 2000). The culture was prepared in the previously mentioned LMM medium in a 96-well microplate, following incubation in an anaerobic chamber at 35\u0026deg;C. After 14-day, we used BacTiter-GloTM Microbial Cell Viability Assay to measure luciferase luminescence using a Thermo Scientific Varioskan Lux.\u003c/p\u003e\n\u003ch3\u003eBiosurfactant production and growth in hydrocarbon medium\u003c/h3\u003e\n\u003cp\u003eAll microorganisms were tested for their ability to produce biosurfactants using the drop collapse technique described by A. Bodour and Miller-Maier (1998). Briefly, the inoculum was prepared in TSB medium and then incubated at 30\u0026deg;C and 200 rpm for 24 or 48 hours, depending on the bacterium growth rate. Bacteria that showed positive results in the initial test had the surface tension of the growth medium measured using a Dataphysics tensiometer and the DCATS 31 software to confirm the reduction in surface tension. To assess the growth of the strains using hydrocarbons as the sole carbon source, the strains were grown in MSM medium with 2% (v/v) hexadecane for 15 days. After this time, resazurin was added as an activity indicator (active cells reduce resazurin to resorufin, a pink compound).\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eSynthesis of exopolysaccharides\u003c/h2\u003e \u003cp\u003eWe assessed synthesis of exopolysaccharide by streaking the strains on Luria-Bertani Agar (LBA) containing 0.2 g L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e Calcofluor. Fluorescent colonies under UV-C light exposure were considered positive for exopolysaccharide production (Leigh et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e1985\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eEnzymatic production\u003c/h3\u003e\n\u003cp\u003eEnzyme production was assessed in 0.1X LBA medium with 10 g L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003etemperature and at 50\u0026deg;C for the others, at 200 rpm for 24 or 48 hours, depending on the strain. The OD\u003csub\u003e600\u003c/sub\u003e were determined and normalized to 0.1, and 10 \u0026micro;L of the culture was spotted onto plates containing the enzyme substrates. The plates were then incubated at 30\u0026deg;C or 50\u0026deg;C. The presence of the enzymes was determined by the appearance of clear zones around the culture.\u003c/p\u003e"},{"header":"RESULTS AND DISCUSSION","content":"\u003cdiv id=\"Sec11\"\u003e\n \u003ch2\u003eIdentification\u003c/h2\u003e\n \u003cp\u003eFatty acids analysis did not provide clear identification at the species level, except for CaSRM9, identified as \u003cem\u003eBacillus licheniformis\u003c/em\u003e (SIM index \u0026gt; 0.8). The SIM index was between 0.6 and 0.8 for five strains identified as \u003cem\u003eBacillus\u003c/em\u003e, which agreed with the phylogenetic analysis using rRNA 16s. The phylogenetic analysis suggests that most strains belong to the \u003cem\u003eBacillus\u003c/em\u003e genus clade (Gupta et al. 2020; Spring et al. 1996). The predominance of \u003cem\u003eBacillus\u003c/em\u003e among strains isolated from saline medium aligns with previous studies that frequently report halotolerant \u003cem\u003eBacillus\u003c/em\u003e worldwide (Nas et al. 2021; Nimkande et al. 2023; Orhan and Gulluce 2015; Reang et al. 2024). Table 1 presents the strains along with their classification based on fatty acid composition as well as their respective isolation sites. Figure 2 illustrates the phylogenetic relationships among the strains and closely related species.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec12\"\u003e\n \u003ch2\u003eSodium chloride tolerance\u003c/h2\u003e\n \u003cp\u003eAll 20 tested strains were able to withstand 100 g L\u003csup\u003e− 1\u003c/sup\u003e NaCl, with CaSRM5 showing the highest mean specific growth rate at this salt concentration (µ = 0.326 h\u003csup\u003e− 1\u003c/sup\u003e). Eleven strains were able to grow at 150 g L\u003csup\u003e− 1\u003c/sup\u003e, with CaSDR7 reaching the highest specific growth rate at this salt concentration (µ = 0.241 h\u003csup\u003e− 1\u003c/sup\u003e). This strain did not perform as well at the lower salt concentration (µ = 0.125 h\u003csup\u003e− 1\u003c/sup\u003e). Only CaSS7 was able to grow at 200 g L\u003csup\u003e− 1\u003c/sup\u003e, albeit very slowly (µ = 0.0164 h\u003csup\u003e− 1\u003c/sup\u003e). Despite being able to withstand higher concentrations of NaCl, CaSS7 presented lower µ values at lower salt concentrations compared to the other strains (µ = 0.060 h\u003csup\u003e− 1\u003c/sup\u003e at 100 g L\u003csup\u003e− 1\u003c/sup\u003e and 0.032 at 150 g L\u003csup\u003e− 1\u003c/sup\u003e). These results indicate no direct relation between the growth rate in the presence of NaCl and tolerance to higher concentrations of this salt. ANOVA assumptions were not met by the µ values at 100 and 150 g L\u003csup\u003e− 1\u003c/sup\u003e. Therefore, we analyzed the data using the Kruskal-Wallis test and Dunn test, which showed significant differences among the strains. Using the suggested classification of Larsen (1986), the strains obtained in this study were classified as moderate halotolerant (organisms which withstand up to 180 or 200 g L\u003csup\u003e− 1\u003c/sup\u003e NaCl) (Table 2).\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eTable 1\u0026nbsp;\u003c/strong\u003eIdentification of Strains Using FAME (MIDI Sherlock), Including Isolation Sites and Similarity Indices.\u003c/p\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"482\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eStrain\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eSite\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eID FAME (SIM index)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSDR1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eDune rhizospheric soil\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cem\u003eBacillus megaterium\u0026nbsp;\u003c/em\u003e(0.593)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSDR7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eDune rhizospheric soil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cem\u003ePseudomonas oryzihabitans (\u003c/em\u003e0.282)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSDA4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eDune bare soil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cem\u003eBrevibacillus formosus\u0026nbsp;\u003c/em\u003e(0.319)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaPFR3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePraia do Farol rhizospheric soil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cem\u003eBacillus subtilis\u0026nbsp;\u003c/em\u003e(0.693)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaPFR7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePraia do Farol rhizospheric soil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cem\u003ePaenibacillus macerans\u003c/em\u003e (0.414)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eBrine rhizospheric soil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eBrine rhizospheric soil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cem\u003eBacillus alcalophilus\u003c/em\u003e (0.366)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eBrine rhizospheric soil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eBrine rhizospheric soil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cem\u003eBacillus pumilus\u003c/em\u003e (0.642)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSS7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eBrine bare soil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSS10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eBrine bare soil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cem\u003eBacillus pumilus\u0026nbsp;\u003c/em\u003e(0.621)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMangrove rhizospheric soil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cem\u003eBacillus atrophaeus\u0026nbsp;\u003c/em\u003e(0.696)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMangrove rhizospheric soil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cem\u003eBacillus\u0026nbsp;\u003c/em\u003esp\u003cem\u003e.\u0026nbsp;\u003c/em\u003e(0.209)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMangrove rhizospheric soil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMangrove rhizospheric soil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cem\u003eBacillus\u0026nbsp;\u003c/em\u003esp\u003cem\u003e.\u0026nbsp;\u003c/em\u003e(0.406)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMangrove rhizospheric soil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cem\u003eBacillus licheniformis\u0026nbsp;\u003c/em\u003e(0.812)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMangrove rhizospheric soil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMangrove rhizospheric soil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cem\u003eMicrobacterium barkeri\u0026nbsp;\u003c/em\u003e(0.575)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMangrove rhizospheric soil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cem\u003eBacillus subtilis\u0026nbsp;\u003c/em\u003e(0.627)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMangrove rhizospheric soil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cem\u003eHalomonas aquamarina\u003c/em\u003e (0.425)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cdiv\u003e\n \u003cdiv align=\"left\"\u003e*A similarity index (SIM index) \u0026lt; 0.6 indicates low similarity, 0.6-0.8 indicates moderate similarity, and \u0026gt;0.8 indicates high similarity. Five strains did not match any entries in the MIDI Sherlock TSB library.\u003c/div\u003e\n \u003cdiv align=\"left\"\u003e\u003cstrong\u003eTable 2 -\u0026nbsp;\u003c/strong\u003eSpecific growth rates (μ) of the bacterial strains at 100 g L\u003csup\u003e-1\u003c/sup\u003e and 150 g L\u003csup\u003e-1\u003c/sup\u003e NaCl. Strains labeled with different letters indicate significant differences of their respective specific growth rates at the same concentration of NaCl (p \u003cstrong\u003e≤\u0026nbsp;\u003c/strong\u003e0.05).\u003c/div\u003e\n \u003c/div\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eBacterial\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eStrain\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"4\" valign=\"top\"\u003e\n \u003cp\u003e----------------------------- NaCl concentration -----------------------------\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;100 g L\u003csup\u003e\u0026nbsp;-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e150 g L\u003csup\u003e\u0026nbsp;-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean μ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMedian μ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean μ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMedian μ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaDA4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.1812\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.179 abc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.124\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.126 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaDR1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.137\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp; 0.137 abc \u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaDR7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.125\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.125 abc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.241\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.241 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaPFR3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.159\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.166 abc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaPFR7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.233\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.233 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.113\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.115 abc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.102\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.095 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.074\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.071 bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.145\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.147 abc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.182\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.183 abc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.168\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.168 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.147\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.147 abc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.048\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.049 bc\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.326\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.323 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.137\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.119 abc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.165\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.165 abc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.026\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.034 c\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.277\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.275 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.102 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.080\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.080 abc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.053\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.054 bc\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.128\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.160 abc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.179\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.175 abc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.051\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.051 c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.068\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.061 bc\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSS10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.076\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.074 bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.016\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.016 c\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSS7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.060\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.063 c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.032\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.032 c\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec13\"\u003e\n \u003ch2\u003eSodium perchlorate tolerance\u003c/h2\u003e\n \u003cp\u003eThe µ values obtained during the perchlorate tolerance experiment did not meet ANOVA assumptions at concentrations of 10 to 90 g L\u003csup\u003e− 1\u003c/sup\u003e (Tables 3 and 4). As a result, we used the Kruskal-Wallis test and the Dunn test. However, at 110 g L\u003csup\u003e− 1\u003c/sup\u003e, we performed ANOVA and the Tukey test (Table 5).\u003c/p\u003e\n \u003cdiv\u003e\n \u003cp\u003e\u003cstrong\u003eTable 3\u0026nbsp;\u003c/strong\u003eSpecific growth rates (μ) of the bacterial strains in medium containing NaClO₄. Strains labeled with different letters indicate significant differences at the same concentration of NaClO₄ (p \u003cstrong\u003e≤\u0026nbsp;\u003c/strong\u003e0.05).\u003c/p\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eBacterial\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003estrain\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"6\" valign=\"top\"\u003e\n \u003cp\u003e----------------------------- NaClO₄ concentration -----------------------------\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e10 g L\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e30 g L\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e50 g L\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean μ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMedian μ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean μ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMedian μ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean μ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMedian μ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaDA4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.171\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.169 ghi*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.147\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.162 efg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaDR1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.156\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.167 ghi\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.171\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.169 cdefg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.186\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.184 bcdefg\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaDR7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.095\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.099 i\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.170\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.171 cdefg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.145\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.147 cdefgh\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaPFR3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.226\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.213 defg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.162\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.160 defg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.117\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.112 efgh\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaPFR7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.158\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.156 ghi\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.120\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.118 g\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.226\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.225 abcde\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.389\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.377 abcd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.534\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.546 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.328\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.389 abc\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.217\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.225 fgh\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.189\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.182 cdefg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.081\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.073 gh\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.347\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.343 abcdef\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.178\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.174 cdefg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.219\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.227 abcde\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.358\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.354 abcdef\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.231\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.224 abc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.266\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.252 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.429\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.443 abc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.518\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.522 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.351\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.396 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.114\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.114 hi\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.185\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.185 bcdef\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.134\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.126 defgh\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.251\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.262 cdefg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.224\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.238 abcd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.094\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.082 fgh\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.451\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.444 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.325\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.331 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.259\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.251 abc\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.237\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.229 defg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.174\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.173 cdefg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.144\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.138 cdefgh\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.212\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.213 efgh\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.213\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.220 abcde\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.042625\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.050 h\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.374\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.371 abcde\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.263\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.276 abc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.240825\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.213 abcde\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.243\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.222 efgh\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.233\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.234 abcde\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.235625\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.244 abcd\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.260\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.254 bcdefg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.140\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.152 fg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.209900\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.206 abcdef\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSS10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.560\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.537 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.471\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.455 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.576775\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.574 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSS7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.187\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.177 ghi\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.186\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.195 bcdefg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.042800\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.042 h\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003cstrong\u003eTable 4\u0026nbsp;\u003c/strong\u003eSpecific growth rates (μ) of the bacterial strains in medium containing 70 \u0026nbsp; 110 g L\u003csup\u003e-1\u003c/sup\u003e NaClO₄. Strains labeled with different letters indicate significant differences at the same NaClO₄ concentration. For concentrations of 70 and 90 g L\u003csup\u003e-1\u0026nbsp;\u003c/sup\u003eNaClO₄\u003csup\u003e\u0026nbsp;\u003c/sup\u003ewe performed Kruskal-Wallis and the Dunn statistical test and for 110 g L\u003csup\u003e-1\u0026nbsp;\u003c/sup\u003eNaClO₄ we performed ANOVA and Tukey test (p \u003cstrong\u003e≤\u0026nbsp;\u003c/strong\u003e0.05).\u003c/p\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eBacterial\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp; strain\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"6\" valign=\"top\"\u003e\n \u003cp\u003e----------------------------- NaClO₄ concentration -----------------------------\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e70 g L\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e90 g L\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e110 g L\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean μ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMedian μ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean μ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMedian μ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean μ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMedian μ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaDR1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.545\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.536 a*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.122\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.107 efgh\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaDR7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.240\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.230 cdef\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.161\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.160 bcd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaPFR3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.152\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.150 fghi\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.131\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.125 defgh\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.152 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.162\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaPFR7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.313\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.320 abc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.303\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.286 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.077\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.082 ghi\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.287\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.291 bcde\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.227\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.230 abcd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.105 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.124\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.317\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.306 abcd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.203\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.206 abcde\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.259 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.245\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.381\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.366 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.245\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.248 abc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.140 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.147\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.175\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.175 defg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.190\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.175 bcd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.176 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.223\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.164\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.155 efgh\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.290\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.29150 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.104 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.096\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.138\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.137 fghi\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.058\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.04885 gh\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.151 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.131\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.155\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.155 fghi\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.183\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.18350 bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.152 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.154\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.356\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.316 abc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.272\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.27350 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.094 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.086\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.034\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.033 hi\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.023\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.02255 h\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.055 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.042\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.298\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.288 bcd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.193\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.18595 bc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.095 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.097\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.379\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.380 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.237\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.23720 abc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.138 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.127\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.096\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.101 ghi\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.039\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.03830 h\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.066 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.067\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSS10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.289\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.282 bcde\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.222\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.22065 abcd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSS7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.027\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.028 i\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.082\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.08610 fgh\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.137 ab\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.132\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003cstrong\u003eTable 5\u0026nbsp;\u003c/strong\u003eBiosurfactant Production by the halotolerant bacterial strains. Surface tension was measured only for bacteria that showed positive results in the drop collapse test. Additionally, growth in MSM medium containing hexadecane as the sole carbon source was assessed.\u003c/p\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eStrain\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDrop collapse\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eSurface tension\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eGrowth on hydrocarbon\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSDR1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e+\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSDR7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e+\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSDA4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaPFR3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e+\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e29.187 +/- 0.025\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaPFR7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e+\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e30.350 +/- 0.023\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e+\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSS7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSS10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e+\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e29.511 +/- 0.029\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e+\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e45.910 +/- 0.029\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e+\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e+\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e27.716 +/- 0.018\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;*NE = Not Evaluated\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eTable 6\u0026nbsp;\u003c/strong\u003eProduction of amylases, lipases and proteases by the strains.\u003c/p\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eStrain\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eamylases\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003elipases\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eproteases\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaDR1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaDR7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSDA4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaPFR3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaPFR7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRM18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSRS10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSS7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCaSS10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e-\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\u003eCaSDA4 showed a high µ at NaCl concentrations of 100 and 150 g L\u003csup\u003e− 1\u003c/sup\u003e, but could not tolerate more than 30 g L\u003csup\u003e− 1\u003c/sup\u003e NaClO₄. This aligns with previous studies that reported a higher tolerance to chloride compared to perchlorate salts (Flores et al. 2020; Heinz et al. 2019). CaSS10 and CaSRM18 exhibited higher growth rates at 10, 30, 50, and 110 g L\u003csup\u003e− 1\u003c/sup\u003e NaClO₄ compared to other strains, but did not perform as well in the NaCl tolerance experiment. This indicates that there is no direct relationship between tolerance to NaCl and NaClO₄. Perchlorate is likely hazardous due to its chaotropic and oxidative nature, while NaCl induces osmotic stress (Heinz et al. 2021; Saini et al. 2023). Therefore, the lack of correlation between the µ values observed in the two experiments may reflect differences in the degree of destabilization caused by these two stressors and in the mechanisms of cell damage caused by each of them.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec14\"\u003e\n \u003ch2\u003ePerchlorate reduction\u003c/h2\u003e\n \u003cp\u003eDuring anaerobic growth on NaClO₄ as electron acceptor, the bacterial strains CaSRS1, CaSRS8, CaSRM5, CaSRM7, CaSRM12, and CaSRM16 formed cell aggregates that could not be disrupted even with intense vortexing (Fig. 3). Microscopic aggregates were also observed for the other strains (Fig. 4). This agrees with previous studies that reported aggregate formation as a response to perchlorate toxicity (Heinz et al., 2019). With the exceptions of CaSS7 and CaSRM7, all microorganisms produced detectable biomass (Fig. 5A). Among these, CaDR1 exhibited the highest biomass, and CaDR1 and CaDR7 demonstrated the highest luciferase luminescence in the ATP assay. This assay indicated that all strains showed luciferase luminescence, demonstrating their viability in a medium where perchlorate served as the sole electron acceptor (Fig. 5B). The ability to not only tolerate perchlorate but also utilize it for respiration is particularly significant in astrobiology, especially in the context of an anoxic Mars with brines rich in perchlorate salts. These organisms could serve as models for studying Mars's habitability and raise concerns about interplanetary contamination. Their capacity to withstand and respire perchlorate makes them potential contaminants of Mars. Furthermore, \u003cem\u003eBacillus\u003c/em\u003e species can form endospores, enhancing their resilience to conditions found on Mars and in spacecraft (Mettler et al., 2023).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec15\"\u003e\n \u003ch2\u003eBiosurfactant production and growth on hydrocarbon\u003c/h2\u003e\n \u003cp\u003eIn the drop collapse test, CaPFR3, CaPFR7, CaSRM5, CaSRM8, and CaSRM18 showed positive results and were further tested for reduction of surface tension in TSB medium (Table 5). The surface tension of the growth medium was 72. All the above isolates could reduce the surface tension of the medium. The lowest surface tension was obtained in the medium inoculated with CaSRM18 (27.716 +/- 0.018). This biosurfactant producing bacterium was the only able to growth in MSM medium containing hydrocarbon as the sole carbon source (see below). Other bacteria capable of growing using hydrocarbon as the sole carbon source (CaSDR1, CaSDR7, CaSRS10, and CaSRM15) did not produce biosurfactant in the tested conditions. Halotolerant \u003cem\u003eBacillus\u003c/em\u003e are known for producing biosurfactants. For example, a marine \u003cem\u003eBacillus licheniformis\u003c/em\u003e could reduce surface tension of the growth medium by 31.4% and degrade engine oil (Nayak et al. 2020). Accordingly, \u003cem\u003eBacillus halotolerans\u003c/em\u003e, isolated from metal-contaminated soil, produces biosurfactants with potential antioxidant, antimicrobial, and anticancer properties (Etemadzadeh \u003cem\u003eet al\u003c/em\u003e. 2024).\u003c/p\u003e\n \u003cp\u003eBiosurfactants have various applications beyond the oil industry, including use in detergents, food, cosmetics, pharmaceuticals, agriculture, and nanotechnology (Sarubbo et al. 2022). Therefore, even strains that cannot use hexadecane or other hydrocarbons as the sole carbon source can be a source of biosurfactants for a variety of applications.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec16\"\u003e\n \u003ch2\u003eSynthesis of exopolysaccharides\u003c/h2\u003e\n \u003cp\u003eSixteen among the 20 bacterial strains showed positive results for exopolysaccharide synthesis (Fig. 6). The production of exopolysaccharide (EPS) aligns with the observations of aggregate formation during perchlorate reduction experiments, as these polymers play a crucial role in cellular aggregation and adherence. Halophilic and halotolerant bacteria synthesize exopolysaccharides (EPS) as a survival mechanism when exposed to harsh conditions. These polymers can exhibit biosurfactant properties and, therefore, contribute to bioremediation (Ibrahim et al., 2020). In addition to bioremediation, EPS also finds applications in the food, pharmaceutical, and agricultural industries. Moreover, EPS is utilized in waste treatment due to its metal chelation, flocculation, and colloid formation properties. Research has shown that EPS produced by \u003cem\u003eBacillus\u003c/em\u003e spp. isolated from mangrove ecosystems demonstrated antimicrobial, cytotoxic, antioxidant, and anti-inflammatory activities, highlighting the importance of studying EPS-producing strains from these and other underexplored ecosystems (Díaz-Cornejo et al., 2023). Additionally, exopolysaccharides produced by this genus were capable of inhibiting biofilm formation by \u003cem\u003eStaphylococcus aureus\u003c/em\u003e, a pathogen associated with bovine mastitis in veterinary medicine (Sabino et al. 2023).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec17\"\u003e\n \u003ch2\u003eEnzymatic production\u003c/h2\u003e\n \u003cp\u003eAll the bacterial isolates produced at least one of the three enzymes evaluated (Table 6). Lipase and protease were produced more frequently (16 and 14 out of 20 bacterial isolates, respectively). In contrast, only 6 isolates produced amylase. Notably, CaSRM5 and CaSRM16 produced all three enzymes, while five isolates produced just one enzyme: CaSDA4 and CaSRS8 produced proteases; CaSRM8 produced amylases; and CaSRM18, CaSS7, and CaSS10 produced lipases.\u003c/p\u003e\n \u003cp\u003eThe production of hydrolases by salt-tolerant bacteria was reported by Drissi Kaitouni et al. (2020), who isolated bacteria from a salt mine and two salt marshes. From 227 bacteria collected, they found that 189 synthesized hydrolases, including amylases and proteases. Additionally, Fatholahpoor et al. (2020) isolated salt-tolerant bacteria from the Eshtehard Desert in Iran, and reported that out of 32 strains, 18 exhibited lipase activity, 12 showed protease activity, and 11 had amylase activity. These enzymes, aside from their role in wastewater treatment, have applications in various industries, such as food, pharmaceuticals, and detergents, among others (Mesbah 2022; Mokasheet al. 2018; Qiu et al. 2021).\u003c/p\u003e\n\u003c/div\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eBrazil possesses significant potential for a vast microbial biodiversity with various applications. Our study focused on the biotechnological and astrobiological applications of halotolerant bacteria isolated from different habitats in a microbiologically underexplored region (Camocim, CE). These microorganisms can tolerate high concentrations of NaCl and perchlorate, a toxic salt commonly found on Mars. Moreover, they can utilize sodium perchlorate as a sole electron acceptor in anaerobic conditions, making them excellent astrobiological models and candidates for survival experiments under simulated anoxic Martian environments. In terms of biotechnological applications, five of the 20 microorganisms produced biosurfactants, while 16 produced exopolysaccharides, both of which have numerous industrial and biotechnological applications. Additionally, these microorganisms produce the enzymes lipases, proteases, and amylases, which are applicable in various industrial sectors.\u003c/p\u003e \u003cp\u003eThis study highlights the importance of improving prospection efforts to unravel the microbial diversity, particularly of extremophiles, and lays the groundwork for future research. Upcoming studies should focus on using omics technologies to better understand the mechanisms behind perchlorate tolerance and reduction by these organisms, as well as assess their specific industrial applications.\u003c/p\u003e"},{"header":"Declarations","content":"\n\u003cp\u003e\u003cstrong\u003eConflict of Interest Statement\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;The authors declare no conflicts of interest related to this work.\u003c/p\u003e\n"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAli N, Nughman M, Shah SM. Extremophiles and limits of life in a cosmic perspective. In: Najjari A, editor. Life in extreme environments: diversity, adaptability and valuable resources of bioactive molecules. London: IntechOpen; 2023. https://doi.org/10.5772/intechopen.110471.\u003c/li\u003e\n\u003cli\u003eAshkenazy Y, Tziperman E. Dynamic Europa ocean shows transient Taylor columns and convection driven by ice melting and salinity. Nat Commun. 2021;12:6376. https://doi.org/10.1038/s41467-021-26710-0.\u003c/li\u003e\n\u003cli\u003eBruce RA, Achenbach LA, Coates JD. Reduction of (per)chlorate by a novel organism isolated from paper mill waste. Environ Microbiol. 1999;1:319-29. https://doi.org/10.1046/j.1462-2920.1999.00042.x.\u003c/li\u003e\n\u003cli\u003eCamara MR. Salinas: ambientes extremos no nordeste do Brasil. In: Viana DL, Oliveira JEL, Hazin FHV, Souza MAC, editors. Ci\u0026ecirc;ncias do mar: dos oceanos do mundo ao Nordeste do Brasil: oceano, clima, ambientes e conserva\u0026ccedil;\u0026atilde;o. Recife: Via Design Publica\u0026ccedil;\u0026otilde;es; 2021. p. 219-29.\u003c/li\u003e\n\u003cli\u003eCardoso AM, Vieira RP, Paranhos R, Clementino MM, Albano RM, Martins OB. Hunting for extremophiles in Rio de Janeiro. Front Microbiol. 2011;2:100. https://doi.org/10.3389/fmicb.2011.00100.\u003c/li\u003e\n\u003cli\u003eCharney J, Tomarelli RM. 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Chem Eng J. 2023;473:145285. https://doi.org/10.1016/j.cej.2023.145285.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Perchlorate reduction, Enzymatic production, Brazilian microorganisms, Salt tolerance","lastPublishedDoi":"10.21203/rs.3.rs-6958968/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6958968/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eHalotolerant bacteria possess significant scientific and biotechnological potential due to their ability to thrive in high-salinity environments and withstand other harsh conditions. Their adaptive mechanisms\u0026mdash;such as the production of exopolysaccharides, specialized enzymes, and biosurfactants\u0026mdash;enable applications in bioremediation, saline wastewater treatment, and industries like food, medicine, and detergents. Notably, these bacteria can tolerate not only NaCl but also other salts, including perchlorates, which are highly toxic and abundant on Mars, where they contribute to liquid water stability.In this study, we isolated halotolerant bacteria from underexplored sites in Camocim, Cear\u0026aacute;, Brazil, and investigated their potential for biotechnological and astrobiological applications. We assessed their tolerance to NaCl and perchlorate, as well as their ability to produce biosurfactants, exopolysaccharides, and enzymes (amylase, lipase, and protease). Additionally, we evaluated their capacity to grow under anoxic conditions using sodium perchlorate as a terminal electron acceptor\u0026mdash;a key trait for survival in Mars-like environments. Among the 20 isolates, predominantly identified as \u003cem\u003eBacillus\u003c/em\u003e sp., all tolerated NaCl concentrations up to 150 g L⁻\u0026sup1;, with \u003cem\u003eBacillus\u003c/em\u003e sp. CaSS7 growing at the maximum tested concentration of 200 g L⁻\u0026sup1;. Most strains also withstood sodium perchlorate at 110 g L⁻\u0026sup1;. Interestingly, NaCl and perchlorate tolerance were not correlated, suggesting distinct stress responses and cellular damage mechanisms for each salt. All isolates produced at least one tested enzyme, 16 synthesized exopolysaccharides, and five were biosurfactant producers. Furthermore, their ability to utilize perchlorate as an electron acceptor under anoxic conditions highlights their potential relevance in astrobiology. This study underscores the importance of expanding bioprospecting efforts to uncover novel applications of halotolerant bacteria and sets the foundation for future research in biotechnology and planetary science.\u003c/p\u003e","manuscriptTitle":"Halotolerant Bacteria From Camocim, Brazil: Prospects for Astrobiology and Biotechnology","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-24 10:09:57","doi":"10.21203/rs.3.rs-6958968/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"6db10524-d1a1-4a5a-9705-2425d75b34d4","owner":[],"postedDate":"June 24th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-07-22T13:23:15+00:00","versionOfRecord":[],"versionCreatedAt":"2025-06-24 10:09:57","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6958968","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6958968","identity":"rs-6958968","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}