Phosphate Solubilization by Microorganisms in Pyroclastic Material from Half Moon Island in Antarctica: Implications for Astrobiology

Phosphate Solubilization by Microorganisms in Pyroclastic Material from Half Moon Island in Antarctica: Implications for Astrobiology | 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 Phosphate Solubilization by Microorganisms in Pyroclastic Material from Half Moon Island in Antarctica: Implications for Astrobiology María Angélica Leal Leal, David Tovar, Alexis Infante, Oscar Barriga, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5358122/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 23 Jan, 2025 Read the published version in Polar Biology → Version 1 posted 11 You are reading this latest preprint version Abstract Microorganisms play a crucial role in the phosphorus cycle, as they mineralize and immobilize organic phosphorus and solubilize and precipitate the inorganic fraction of it. In various regions of the planet, the functional capacity of microorganisms in the solubilization process has been evaluated; however, in polar regions, the difficulty in accessing samples and handling microorganisms presents a limitation for understanding this cycle. This study aimed to evaluate the phosphate-solubilizing capacity of cultivable microorganisms present in volcanic soils of Half Moon Island in Antarctica and their astrobiological implications for Mars. Physicochemical soil analysis, traditional culture techniques, selective media cultivation, and enzymatic activity analysis for soil phosphatase were conducted. Growth of various isolates was observed across different sampling points, with phosphate-solubilizing activity ranging from 14.29–92.31% of the isolates at each sampling point. These bacteria showed a direct relationship with soil calcium content. Phosphatase activity recorded low values, possibly affected by temperature and the low metabolic rate of in situ microorganisms. The findings suggest that microorganisms in Antarctic volcanic soils could contribute to astrobiological exploration on Mars. Phosphorus cycle acid phosphatase alkaline phosphatase nutrient cycling Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 1. Introduction Historically, Mars has captivated the scientific community and is considered a planetary body with potential for looking for life outside the Earth, as well as a terrestrial planet with similar ancient conditions to promote the emergence of life on its early geological stages (Camprubí et al., 2019 ). This hypothesis stems from the discovery of various microorganisms inhabiting extreme environments on Earth, considered analogs of Mars (Joseph et al., 2019 ). One such place is Antarctica, where three Martian analogs have been identified: Dry Valleys, North Victoria Land Mountains, and Lake Vostok. These regions share extreme conditions, including low temperatures, strong winds, permafrost, and isolation (Anderson et al., 1972 ; Meeßen et al., 2015 ; Martins et al., 2017 ). These analogs allow us to understand various aspects of the planetary body to which the analogy is drawn. Some terrestrial analogs facilitate understanding of planetary processes, mineralogy, and even the different adaptations that life might develop in such physiologically stressful environments (Foucher et al., 2021 ). On the other hand, in several regions of Antarctica, such as the South Shetland Islands, the phosphorus cycle is poorly understood. In other areas, like the McMurdo Dry Valleys, it is known that tills (poorly sorted, unstratified glacial deposits) represent the largest phosphorus reserves, although transport rates have not been quantified (Bate et al., 2008 ; Zeglin et al., 2009 ). The global phosphorus cycle and its interactions play a fundamental role in climate modeling and landscape formation (Xu et al., 2013 ). Phosphorus is an essential component in all known life forms on our planet due to its role in biomolecules such as DNA, phospholipids, and ATP, among others (Sylvia et al., 2005 ). There are two main sources that supply phosphate: 1) guano, formed from bird excrement, and 2) apatite, rocks with high concentrations of calcium phosphate (Fillippelli & Souch, 1999 ; Bate et al., 2008 ). The phosphorus cycle is often influenced by the composition of parent material and in situ rates of processes, including weathering, biological uptake, and cycling. Since phosphorus is affected by both biological and chemical reactions, a straightforward way to understand these interactions is to divide the phosphorus cycle into two sub-cycles: 1) geochemical and 2) biological. In the geochemical sub-cycle, minerals are solubilized into orthophosphate through chemical and biochemical weathering processes. The release of orthophosphate into soil solution, which is subsequently absorbed by plants and microorganisms, occurs through the dissolution of compounds by microbiologically produced organic acids (Smeck, 1985 ; Sylvia et al., 2005 ). In the biological sub-cycle, orthophosphate is either stored by plants or immobilized by microbial biomass. Plant and/or animal waste reincorporates organic phosphorus into the soil in three different ways: i) stable humus, ii) as mineralized orthophosphate, or iii) as immobilized microbial biomass. Phosphorus from biomass is also incorporated into humic substances, mineralization, and immobilization reactions (Bate et al., 2008 ; Zheng et al., 2022 ). On Half Moon Island, very little is known about microbiology, and considering that nutrient mobilization in Antarctica is largely due to microorganisms, their relationship with nutrient cycling, specifically the phosphorus cycle, is also unknown. This study aims to evaluate the capacity of microorganisms present in the pyroclastic material of Half Moon Island to solubilize phosphates and their relevance to astrobiological studies on Mars. 2. Materials and Methods 2.1. Study Area, Sample Collection, and Mapping The samples were collected on Half Moon Island (S 62° 35’; W 59° 55’), South Shetland Islands, in the northern region of the Antarctic Peninsula, between Drake Passage and Bransfield Sea (Fig. 1 A), during the Antarctic summer of 2015–2016, specifically in February. During the sample collection, the average air temperature was 0.609°C, with an ambient humidity of 93.648%, solar radiation of 130.175 W/m², wind speed of 32.564 km/h, and atmospheric pressure of 981.272 hPa, according to data from the oceanographic sailing vessel Bernardo Houssay, operated by The Argentine Naval Prefecture, anchored in Moon Bay. Sampling was conducted in a Z-pattern across the island, at five different points where sediment remained frozen for most of the year and located away from areas heavily impacted by humans, to ensure the presence of native microbiota (sampling points P1, P2, P3, P4, P5) (Fig. 1 B). Additionally, a control sample was taken from an area with a snow or ice layer and significant human intervention, selecting a penguin colony due to the high influx of tourists (sampling point P6) (Fig. 1 B). At each point, an individual sediment sample was collected from a depth of 2 to 15 cm, placed in sterile bags, and preserved in cold conditions until transported to the laboratory (4°C). 2.2 Physicochemical Analysis of Sediments The sediment samples were analyzed to determine various characteristics, focusing on parameters relevant to sediment studies, including pH and elemental content (P, Ca, N, S). The Bray II method was used for phosphorus extraction, which involves the use of ammonium fluoride in dilute hydrochloric acid (García & Ballesteros, 2006 ). The Walkley-Black method was employed to determine organic carbon, which involves the wet oxidation of the soil sample using potassium dichromate solution. From this, easily oxidizable carbon was calculated, and the total organic carbon percentage was derived using a variable correction factor (Eyherabide et al., 2014 ). The nitrogen content was calculated based on the percentage of organic carbon, using a standardized formula that includes the nitrogen mineralization constant according to climate conditions and the nitrogen availability factor based on soil texture (Brust, 2019 ). This analysis was performed using atomic absorption spectrometry following extraction with 1N ammonium acetate at pH 7. The sulfur content was quantified using a turbidimetric method, while the pH was determined using a saturation paste and a potentiometer. 2.3 Culture of Microorganisms Microorganism isolations were conducted using the methodology established by Harrigan and McCance (Harrigan & McCance, 1966 ). Starting from a mother solution with 10 g of sediment from each sampling point in 90 mL of sterile saline solution (0.9% NaCl), dilution series were performed from 10⁻¹ to 10⁻⁹ with saline solution, plating onto nutrient agar and incubating at 15°C, in triplicate until growth was observed. After obtaining the plating results, countable dilutions (between 30 and 300 CFU/g according to the standard method) were selected (Madigan & Martino, 2006 ), and subcultures were made in nutrient agar for isolation, followed by Gram staining to verify purity. In cases of impure isolates, successive subcultures were performed. Once obtained, the cultures were incubated at 15°C. 2.4 Assessment of phosphate-solubilizing activity in bacteria. To evaluate the inorganic phosphate-solubilizing bacteria, SRS medium was used (0.5 g/L (NH 4 )2SO 4 ; 0.2 g KCl; 0.3 g/L MgSO 4 ; 0.01 g/L MnSO 4 ; 0.01 g/L FeSO 4 ; 0.2 g/L NaCl; 10 g/L glucose; 0.5 g/L yeast extract; 18 g/L agar-agar, distilled water). Bromocresol purple was added, and the pH was adjusted to 7.0-7.5, according to the IGAC protocol (2006). From the isolated colonies, a mass inoculation was performed in the SRS medium containing calcium phosphate salts and bromocresol purple as a pH indicator. After 24 to 48 hours at 15°C, bacterial colonies that acidified the culture medium (color change from purple to yellow) and/or formed a transparent halo around the colony, indicating the production of tricalcium phosphate or solubilizing activity due to presumed enzymatic activity, were identified as positive. 2.5 Identification of microorganisms Genomic DNA was extracted from the strains that presented transparent or yellow halos greater than 15 mm in SRS medium, using the ZR Fungal / Bacterial DNA MiniPrep kit (Zymo Research, USA). The 16S rRNA gene was amplified by PCR under the following conditions (50 µL): 1X Taq polymerase buffer, 1.5 mM MgCl2, 0.2 mM dNTPs, 0.4 µM forward primer 27F (5’-AGAGTTTGATCCTGGCTCAG-3’), 0.4 µM reverse primer 1492R (5’-GGTTACCTTGTTACGACTT-3’), 1.25 U of Taq DNA polymerase GoTaq® Flexi DNA Polymerase (Promega), and 10–100 ng of genomic DNA. The PCR was conducted in a thermocycler (Mastercycler Pro, Eppendorf AG) with the following program: 2 min at 95°C; 30 cycles of 20 s at 94°C, 20 s at 50°C, and 90 s at 72°C; and 10 min at 72°C. The PCR products were sequenced using Sanger sequencing on the ABI 3500 capillary electrophoresis system. The 16S rRNA sequences were compared in GenBank. Multiple alignments of different 16S rRNA sequences of bacteria related to cold environments from the GenBank database were performed using Highly similar sequences (megablast). Phylogenetic analysis was conducted using MEGA 11 software. Unrooted trees were constructed using the Maximum Parsimony method. A bootstrap analysis of 1000 iterations was performed with the dataset. 2.5 Determination of acid and alkaline phosphatase activity (EC 3.1.3.2 and 3.1.3.1, respectively) in sediments. The p-nitrophenol released after incubating sediment samples with p-nitrophenyl phosphate (PNP) solution for 1 hour at 37°C was determined (Alef & Nannipieri, 1995 ). The p-nitrophenol released by the activity of phosphomonoesterase was extracted and colored In a solution of 1.21g of Tris, 1.16g of malic acid, 1g of monohydrated citric acid, and 0.63g of boric acid in 100mL of 1M NaOH. (Adjusted with HCl to pH 6.5 for acid phosphatase and with NaOH to pH 11 for alkaline phosphatase), and finally, photometrically measured at 400 nm, according to the standardized procedure by Avellaneda ( 2008 ) following the protocols of Tabatabai & Bremner ( 1969 ) and Eivazi & Tabatabai ( 1977 ). This procedure was performed on five subsamples for each sampling point and three replicates for each subsample. Subsequently, the mean of the replicates per subsample and the mean of the subsamples were calculated, yielding a unique value per point. Based on the unique absorbance values obtained for each sample and the respective controls, and using the previously determined equation of the line for the calibration curve, the µg PNP · ml⁻¹ were calculated. These were then introduced into the equation presented below to calculate the enzymatic activity expressed as µg PNP · g⁻¹ dm · h⁻¹ (Avellaneda, 2008 ). $$\:\mu\:g\:pNP*{g}^{-1}dm*{h}^{-1}=\frac{\left(S-C\right)*F*V*100}{W*\%dm*t}$$ Where, \(\:S\) = Average value of the samples (µg pNP*mL-1) \(\:C\) = Control (µg pNP *mL-1) \(\:V\) = Volume of the extract (mL) \(\:W\) = Sediment (henceforth called soil) initial weight \(\:{100*\%}^{-1}dm\) = dry soil weight factor = dwt ó Dry weight of 1g of soil \(\:t\) = incubation time (h) \(\:F\) = dilution factor 2.6 Statistical analysis For the statistical analysis, the free software R Commander was used. Principal Component Analysis (PCA) was performed on the data from the physicochemical sediment analysis, phosphatase enzyme activity, and phosphate-solubilizing microbial populations to determine the correlations between the studied variables, establish patterns, and attempt to reduce the number of variables. 3. Results 3.1. Physicochemical Analysis of Sediments Results from sediment analysis are presented in Table 1 . Textural analyses were not considered, given that these classifications apply to formed soils, while the collected samples correspond to highly weathered pyroclasts that have not yet developed a soil matrix; thus, a textural classification would be inaccurate. Table 1 Results of physicochemical analysis of sediments collected on Half Moon Island, Antarctica Sampling point pH P (mg/Kg) C (%) N (Kg/ha) K (mg/Kg) Fe (mg/Kg) Mg (mg/Kg) Ca(mg/Kg) S (mg/Kg) P1 6.78 245.00 0.49% 8.30 206.87 274 90 598 39.7 P2 6.9 2100.00 0.78% 13.14 180.00 494 184 2280 40 P3 6.42 497.00 0.64% 11.00 148.32 355 121.2 1422 21.8 P4 6.77 701.00 0.49% 8.41 121.00 518.00 97.2 430 7.40 P5 5.76 284.00 0.39% 6.70 66.3 564 56.4 256 20 P6 4.16 3156.00 0.76% 13.06 429 824 54 440 9.8 3.2 Culture of microorganisms The cultivation plates incubated at 15°C showed observable growth between 24 and 72 hours after inoculation. Countable growth was present in the 10 − 4 and 10 − 6 dilutions, except for point P5, where countable colonies were observed even at a dilution of 10 − 2 . In dilutions lower than 10 − 6 , growth was insignificant. Figure 2 presents the counts of purified isolates across samples. 3.3 Qualitative assessment of phosphate solubilizing activity The obtained isolates were subsequently evaluated in SRS medium. The percentage of positive growth for potential phosphate solubilization activity (Ca 3 (PO 4 ) 2 ) by sampling point is presented in Fig. 3 . 3.4 Identification of microorganisms Considering the established parameters, six isolates were analyzed using the 16S gene, identifying them as related to Pseudomonas yamanorum , Pseudomonas canavaninivorans , and Pseudomonas libanensis , as shown in Fig. 4 . 3.5 Determination of Acid and Alkaline Phosphatase Activity The enzyme activity by sampling point is presented in Table 2 . Table 2 Phosphatase activity by sampling point. Half Moon Island, Antarctica. Sampling point Acid phosphatase (µg PNP/g dry soil*hour) Alkaline phosphatase (µg PNP/g dry soil*hour) P1 0.30 2.30 P2 0.30 2.27 P3 1.87 0.41 P4 6.90 3.92 P5 6.57 1.99 P6 9.20 5.40 3.6 Statistical analysis According to the principal component analysis, the integrated graph of components 1 and 2 was generated, as shown in Fig. 5 . The first two components were selected because they explain 86.7% of the presented variables. Potential activity of phosphate solubilizing bacteria is indicated by the blue dotted arrow. The different chemical elements, acid and alkaline phosphatase, and each sampling point are presented. 4. Discussion According to Table 1 , it is possible to see that the points with the highest phosphorus content are P6 and P2, respectively. P6 corresponds to the penguin colony, a site highly impacted by tourist influence, as well as by the presence of a colony of Gentoo penguins ( Pygoscelis antarcticus ), whose diet primarily consists of fish, krill, and small crustaceans (Lynnes, Reid, & Croxall, 2004 ). On the other hand, P2 is a sample from the Caleta Menguante beach area, composed of rock fragments. These sediment compositions preliminarily align with what Bate and colleagues ( 2008 ) described, with a greater presence of guano and rock. Although due to its phosphorus content it cannot be classified as phosphorite (since its P 2 O 5 content is less than 4%), its content is significant compared to the other sampling points. Another noteworthy parameter is the pH variation in the contrasting sample P6, where the presence of acidic guano alters the physicochemical properties of the pyroclast (Bate et al., 2008 ; Hopkins et al., 2008 ). The potential activity of phosphate-solubilizing bacteria (based on isolate counts), it was observed that a high percentage exhibited, except for sampling point P5, as shown in Fig. 3 . Additionally, Fig. 5 indicates that the potential solubilizing activity (blue dotted arrow) is completely independent of the phosphorus content in the sediments; instead, a direct relationship was observed with the sulfur and magnesium content, but especially with the calcium content. These results are also like those reported by Bate and colleagues (Bate et al., 2008 ), where the presence of phosphorus in some Antarctic environments is related to its affinity for calcium (Ca) fractions. Interestingly, an inverse correlation was observed between potential solubilizing activity and acid phosphatase activity. A similar relationship was observed with alkaline phosphatase activity and iron content. This behavior may be explained by competitive interactions, as microbial competition in polar soil has been reported to be intensified due the limited access to soil nutrients and space, a dynamic that may be increased during summer (Bell et al., 2013 ). Bertk Pinto et al, (2019) reported a strong correlation between bacterial competition and organic acid contractions in arctic snow, where a higher number of bacterial taxa were associated with higher organic acid levels. This relationship is notable, as organic acids are produced in the phosphate solubilization (Corrales et al., 2014 ). Furthermore, low rates of biological mobilization were found due to the present immobilization and nutrient transformation (Bate et al., 2008 ). This is likely due to biotic factors responsible for the dynamics of the elements, and the abiotic component responsible for the spatial and temporal variability of the phosphate gradients present in Antarctic soils, as the relationship of solubilizing microorganisms with calcium would indicate this P-Ca relationship in the immobilization of the element in Antarctic sediments. This is understandable considering that among the types of inorganic phosphorus used by solubilizing microorganisms are fluorapatite, hydroxyapatite, and tricalcium phosphate, all of which contain calcium in their structure. One of the pathways for phosphorus solubilization is the production of organic acids, which acidify the medium and facilitate phosphorus availability; as they carry negative charges, they can chelate metal ions such as Ca²⁺ and release phosphorus (Corrales et al., 2014 ). This production of organic acids was evidenced in most isolates, indicated by a yellow coloration in the medium due to a shift in the pH indicator (bromocresol purple), which allows us to infer that this would be the most utilized mechanism for phosphorus solubilization, and it would be defined by the calcium content. Regarding phosphatase activity, no relationship was observed between alkaline phosphatase activity and the percentage of microorganisms with solubilizing activity. In contrast, acid phosphatase activity showed a slightly negative relationship with solubilizing activity (Fig. 5 ), considering the orthogonality of the two variables as a function of component 1 and 2. This may be because phosphatase participates in the glucose cycle, facilitating phosphorus solubilization, as this mechanism of periplasmic oxidation of glucose to gluconic acid has been predominantly evidenced in Gram-negative bacteria (Beltrán, 2014 ), such as the genus Pseudomonas. Furthermore, cultivable microorganisms represent only between 0.1% and 1% of the total microbial population present in the soil (Reeder & Knight, 2009 ), so the recorded activity could correspond to microorganisms that are non-viable under laboratory conditions. On the other hand, alkaline and acid phosphatase activity is indeed very low compared to soils with agricultural crop activity; for example, in a soil with soybean cultivation, activities range from 5.72 to 15.5 µg PNP g⁻¹ soil h⁻¹ for alkaline phosphatase and from 27.4 to 105 µg PNP g⁻¹ soil h⁻¹ for acid phosphatase (Fernández et al., 2008 ). In the evaluated sediments, the highest value for acid phosphatase corresponded to 9.20 µg PNP g⁻¹ soil h⁻¹ and 5.40 µg PNP g⁻¹ soil h⁻¹ for alkaline phosphatase at the control point P6, where there is animal activity. In contrast, the lowest value was recorded at 0.30 µg PNP g⁻¹ soil h⁻¹ for acid phosphatase at points P1 and P2, and 0.41 µg PNP g⁻¹ sediment h⁻¹ for alkaline phosphatase at P3. Temperature plays a fundamental role in enzyme activity, as lower than optimal temperatures result in decreased metabolism for its production, with phosphatase typically showing its optimum activity at temperatures close to 37°C (Blanco, 1992 ). The low production of these enzymes is supported by the slow growth rate of the psychrophilic microorganisms that could produce it (Feller and Gerday, 2003 ; Buford & Sowers, 2004 , Fanin et al., 2022 ). The presence of phosphate-solubilizing microorganisms in extreme environments, such as Half Moon Island in Antarctica, is not only crucial for understanding biogeochemical cycles in these ecosystems but also has significant implications for the search for biosignatures on Mars (Berenjian & Seifan, 2022 ). The ability of these microorganisms to release phosphorus from insoluble inorganic compounds into forms available for other organisms could be fundamental for the sustainability of life under extreme conditions, both on Earth and potentially on other planets (Plante, 2007 ; Tian et al., 2021 ; Silva et al., 2023 ). At Half Moon Island, an environment characterized by extreme temperature conditions and high solar radiation, phosphate-solubilizing microorganisms play a crucial role in the availability of this essential nutrient for life. The results obtained in this study indicate that several sampling points on the island showed significant activity of these microorganisms, as evidenced by the presence of specific bioindicators and their ability to acidify the medium, thereby facilitating phosphorus release (Table 2 ; Fig. 3 ). The relevance of these findings extends beyond Antarctica, as the ability of microorganisms to solubilize phosphate could have direct implications for Mars exploration (Röling et al., 2015 ; Hausrath et al., 2024 ). The presence of phosphates in Martian soil has been well documented by missions such as the Mars Rover Curiosity (Grotzinger et al., 2012 ; Grotzinger et al., 2015 ), suggesting that this key element for life may be present in inorganic forms that could be accessible to phosphate-solubilizing microorganisms. The detection of enzymatic activities such as acid and alkaline phosphatase in Antarctic sediments provides a useful model for understanding how these microorganisms might behave in similar Martian environments, where extreme conditions could also promote processes of solubilization of essential nutrients for microbial life (Table 2 ). Furthermore, the association between phosphate solubilizing activity and other elements such as calcium, sulfur, and magnesium in the sediments of Half Moon Island suggests possible complex biochemical interactions (Fig. 5 ) that could be explored as potential biosignatures on Mars. The ability of microorganisms to modify soil chemistry and release essential nutrients could leave specific geochemical markers, detectable through spectroscopy techniques and advanced microscopic analyses in future space exploration missions. Finally, another fundamental aspect in the field of astrobiology is that these types of microorganisms facilitate the mobilization of nutrients to plants. This is why organisms tolerant to low temperatures and other adverse conditions, such as those present in Antarctica, and capable of solubilizing phosphates, could promote plant growth in future manned missions to Mars, ensuring the use of in situ substrates. 5. Conclusions and Perspectives The research on microorganisms with phosphate solubilizing activity in Half Moon Island has provided valuable insights into their role in the phosphorus cycle and their interaction with the Antarctic environment. Below are the conclusions derived from the findings and the future perspectives that arise from this study. These conclusions not only highlight the relevance of these microorganisms in local ecosystems but also suggest lines of research that may contribute to our understanding of life in extreme conditions, both on Earth and on other celestial bodies, such as Mars. 5.1 Conclusions Microbial Activity and the Phosphorus Cycle: The culturable microorganisms identified in Half Moon Island exhibit phosphate solubilization activity, indicating their capacity to significantly contribute to the mineralization and mobilization of phosphorus in this Antarctic environment. This activity suggests that these microorganisms are fundamental to soil biochemistry and may influence the availability of nutrients for other forms of life. Relationship with Chemical Elements: The phosphate solubilization activity in microbial communities may be related to the abundance of other chemical elements in the sediments of Half Moon Island. This suggests the existence of complex biogeochemical networks in which these microorganisms play a crucial role in nutrient interaction and availability. Influence of Temperature: It was observed that temperature directly affects the growth rate of microorganisms and their production of phosphatases. This highlights the importance of climatic conditions in microbial dynamics and their ability to solubilize phosphorus, which is relevant in the context of climate change and its effects on Antarctic ecosystems. Comparison with Other Antarctic Regions: The phosphorus and calcium dynamics observed in Half Moon Island are consistent with those recorded in other areas of the Antarctic Peninsula, suggesting patterns of microbial activity that may be common across various locations on the continent. 5.2 Perspectives Future Studies on Ecological Interactions: Further research is recommended to assess how microorganisms with phosphate solubilization activity interact with plant dynamics in Half Moon Island. Since these microorganisms are crucial for soil formation, studying them will provide better insights into ecosystems and their resilience in extreme environments. Astrobiological Conditions: It is crucial to explore the dynamics of these microorganisms under astrobiological interest conditions, particularly those simulating Martian environments. This may provide valuable information regarding the possibility of microbial life in the past or present on that planet, as well as the potential for these microorganisms to adapt and thrive in extraterrestrial conditions. Implications for Space Missions: Identifying microorganisms capable of phosphate solubilization on Mars should be a serious goal for future space missions. These organisms could not only indicate past conditions conducive to life but could also be used in terraforming strategies or in nutrient production to sustain future crewed missions. Declarations The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Conflict of interest: The authors declare that they have no conflicts of interest. Funding: For the integral development of the same has been supported and funded by counterparts of the authors’ institutions. Author Contribution M.A.L. and D.T., were responsible for conceptualization; investigation; visualization; writing—original draft, writing—review and editing. A.I., O.B. and E.R. contributed to the investigation. J.S. and L.M.M. were in charge of conceptualization, resources, and supervision of the research. Acknowledgement The authors would like to thank the institutions with which they work and collaborate since they are the ones that allow the development of the publication. Additionally, they extend special thanks to the Colombian Antarctic Program and the Argentine Navy for their constant collaboration in Antarctic research, especially in Camara Antarctic Station. Special thanks to the Planetario de Bogotá for the award to the life and work of the science communicator in astronomy and space sciences, granted to the Astrobiology Science Club of the Universidad Nacional de Colombia on its ten-year anniversary in 2015, which was used to fund the research campaign for this study. 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Academic, New York Hausrath EM, Adcock CT, Berger JA, Cycil LM, Kizovski TV, McCubbin FM, Clark BC (2024) Phosphates on Mars and Their Importance as Igneous, Aqueous, and Astrobiological Indicators. Minerals 14(6):591. https://doi.org/10.3390/min14060591 Hocking A, Pitt J (1980) Dichloran-Glycerol Medium for Enumeration of Xerophilic Fungi from Low-Moisture Foods. Appl Environ Microbiol 39(3):488–492. https://doi.org/10.1128/aem.39.3.488-492.1980 Hopkins DW, Sparrow AD, Shillam LL, English LC, Dennis PG, Novis P, Greenfield LG (2008) Enzymatic activities and microbial communities in an Antarctic dry valley soil: responses to C and N supplementation. Soil Biol Biochem 40(9):2130–2136. https://doi.org/10.1016/j.soilbio.2008.03.022 Instituto geográfico Agustín Codazzi IGAC (2006) Métodos analíticos del laboratorio de suelos, Sexta edn. Instituto geográfico Agustín Codazzi, Bogotá Joseph RG, Dass RS, Rizzo V, Cantasano N, Bianciardi G (2019) Evidence of life on Mars. J Astrobiology Space Sci Reviews 1:40–81 Lynnes A, Reid K, Croxall J (2004) Diet and reproductive success of Ade´lie and chinstrap penguins:linking response of predators to prey population dynamics. Polar Biol 27:544–554. https://doi.org/10.1007/s00300-004-0617-1 Madigan M, Martino J (2006) Brock Biologia de los Microorganismos. Pearson, Madrid Martins Z, Cottin H, Kotler JM, Carrasco N, Cockell C, De la Torre R, Westall F (2017) Earth as a tool for astrobiology - A European perspective. Space Sci Rev 209:43–81. 10.1007/s11214-017-0369-1 Matsuoka K, Skoglund A, Roth G (2018) Quantarctica [data set]. Norwegian Polar Insitute Meeßen J, Wuthenow P, Schille P, Rabbow E, de Vera J-P, Ott S (2015) Resistance of the Lichen Buellia frigida to Simulated Space Conditions during the Preflight Tests for BIOMEX—Viability Assay and Morphological Stability. Astrobiology 15(8):601–615. 10.1089/ast.2015.1281 Plante AF (2007) Soil biogeochemical cycling of inorganic nutrients and metals. Soil microbiology, ecology and biochemistry. Academic, pp 389–432 Reeder J, Knight R (2009) The rare biosphere: A reality check. Nat Methods 6(9):636–637 Röling WF, Aerts JW, Patty CL, Kate T, Ehrenfreund IL, P., Direito SO (2015) The significance of microbe-mineral-biomarker interactions in the detection of life on Mars and beyond. Astrobiology 15(6):492–507. https://doi.org/10.1089/ast.2014.1276 Silva LID, Pereira MC, Carvalho AMXD, Buttrós VH, Pasqual M, Dória J (2023) Phosphorus-solubilizing microorganisms: a key to sustainable agriculture. Agriculture 13(2):462. https://doi.org/10.3390/agriculture13020462 Smeck N (1985) Phosphorus dynamics in soils and landscapes. Geodema 36:185–199. https://doi.org/10.1016/0016-7061(85)90001-1 Sylvia D, Hartel P, Fuhrmann J, Zuberer D (2005) Principles and applications of soil microbiology. Pearson Prentice Hall, New Jersey Tabatabai M, Bremner (1969) Use of p-nitrophenyl phosphate for assay of soil phosphatase activity. Soil biology &biochemistry , 301–307. https://doi.org/10.1016/0038-0717(69)90012-1 Tian J, Ge F, Zhang D, Deng S, Liu X (2021) Roles of phosphate solubilizing microorganisms from managing soil phosphorus deficiency to mediating biogeochemical P cycle. Biology 10(2):158. https://doi.org/10.3390/biology10020158 Xu X, Thornton P, Post W (2013) A global analysis of soil microbial biomass carbon, nitrogen and phoshorus in terrestrial ecosystems. Glob Ecol Biogeogr 22:737–749. https://doi.org/10.1111/geb.12029 Zeglin LH, Sinsabaugh RL, Barrett JE, Gooseff MN, Takacs-Vesbach CD (2009) Landscape distribution of microbial activity in the McMurdo Dry Valleys: linked biotic processes, hydrology, and geochemistry in a cold desert ecosystem. Ecosystems 12:562–573. https://doi.org/10.1007/s10021-009-9242-8 Zheng Z, Wang X, Jin J, Hao J, Nie Y, Chen X, Liu X (2022) Fraction distribution and dynamic cycling of phosphorus in lacustrine sediment at Inexpressible Island. Antarctica Environ Int 164:107228. https://doi.org/10.1016/j.envint.2022.107228 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 23 Jan, 2025 Read the published version in Polar Biology → Version 1 posted Editorial decision: Revision requested 26 Nov, 2024 Reviews received at journal 13 Nov, 2024 Reviews received at journal 12 Nov, 2024 Reviews received at journal 11 Nov, 2024 Reviewers agreed at journal 05 Nov, 2024 Reviewers agreed at journal 04 Nov, 2024 Reviewers agreed at journal 02 Nov, 2024 Reviewers invited by journal 02 Nov, 2024 Editor assigned by journal 30 Oct, 2024 Submission checks completed at journal 30 Oct, 2024 First submitted to journal 30 Oct, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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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-5358122","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":374488524,"identity":"b3c5fa1c-cf2f-49bc-af00-7e781b08dc53","order_by":0,"name":"María Angélica Leal Leal","email":"data:image/png;base64,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","orcid":"","institution":"Planetary Sciences and Astrobiology GCPA Research Group, Universidad Nacional de Colombia and Corporación Científica Laguna, 111321 Bogotá, Colombia.","correspondingAuthor":true,"prefix":"","firstName":"María","middleName":"Angélica Leal","lastName":"Leal","suffix":""},{"id":374488525,"identity":"6b17ee46-bc24-45b8-809e-09206e20adff","order_by":1,"name":"David Tovar","email":"","orcid":"","institution":"Planetary Sciences and Astrobiology GCPA Research Group, Universidad Nacional de Colombia and Corporación Científica Laguna, 111321 Bogotá, Colombia.","correspondingAuthor":false,"prefix":"","firstName":"David","middleName":"","lastName":"Tovar","suffix":""},{"id":374488526,"identity":"93eb88e6-4cf9-4a92-9d0b-dde4157459a3","order_by":2,"name":"Alexis Infante","email":"","orcid":"","institution":"Planetary Sciences and Astrobiology GCPA Research Group, Universidad Nacional de Colombia and Corporación Científica Laguna, 111321 Bogotá, Colombia.","correspondingAuthor":false,"prefix":"","firstName":"Alexis","middleName":"","lastName":"Infante","suffix":""},{"id":374488527,"identity":"f6047e4d-fbfd-488e-998d-85c1446521b7","order_by":3,"name":"Oscar Barriga","email":"","orcid":"","institution":"Planetary Sciences and Astrobiology GCPA Research Group, Universidad Nacional de Colombia and Corporación Científica Laguna, 111321 Bogotá, Colombia.","correspondingAuthor":false,"prefix":"","firstName":"Oscar","middleName":"","lastName":"Barriga","suffix":""},{"id":374488528,"identity":"8460d0a6-6169-4dd2-8a3a-25db9248c2f9","order_by":4,"name":"Elkin Marcelo Ruíz","email":"","orcid":"","institution":"Departamento de Biología, Facultad de Ciencias, Universidad Nacional de Colombia, 111321, Bogotá, Colombia.","correspondingAuthor":false,"prefix":"","firstName":"Elkin","middleName":"Marcelo","lastName":"Ruíz","suffix":""},{"id":374488529,"identity":"db0b8888-6b5d-4ed0-8d4c-e2efe29a1ff1","order_by":5,"name":"Jimena Sánchez","email":"","orcid":"","institution":"Departamento de Biología, Facultad de Ciencias, Universidad Nacional de Colombia, 111321, Bogotá, Colombia.","correspondingAuthor":false,"prefix":"","firstName":"Jimena","middleName":"","lastName":"Sánchez","suffix":""},{"id":374488530,"identity":"815c1203-1a54-4b78-b0a6-7a4f7b6da3f8","order_by":6,"name":"Luz Marina Melgarejo","email":"","orcid":"","institution":"Departamento de Biología, Facultad de Ciencias, Universidad Nacional de Colombia, 111321, Bogotá, Colombia.","correspondingAuthor":false,"prefix":"","firstName":"Luz","middleName":"Marina","lastName":"Melgarejo","suffix":""}],"badges":[],"createdAt":"2024-10-30 04:08:22","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5358122/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5358122/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00300-025-03348-y","type":"published","date":"2025-01-23T15:57:30+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":68746836,"identity":"454c7e1e-2bf5-4cc1-b680-e9d5f04c6c21","added_by":"auto","created_at":"2024-11-11 15:28:44","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":384522,"visible":true,"origin":"","legend":"\u003cp\u003eA) Location of Half Moon Island in the South Shetland Islands, B) Map of the distribution of sampling points taken on Half Moon Island, Antarctica, austral summer 2015-2016 (B) (Created by the authors based on Quantarctica v3 (Matsuoka et al., 2018)).\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-5358122/v1/a0fe186f1a878de3b2bf0d20.png"},{"id":68747148,"identity":"4f147aa5-68b3-46e9-927f-25391aee2b88","added_by":"auto","created_at":"2024-11-11 15:36:44","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":4670120,"visible":true,"origin":"","legend":"\u003cp\u003eNumber of isolations obtained through cultivation on nutrient agar by sampling point, Half Moon Island, Antarctica.\u003c/p\u003e","description":"","filename":"Fig.2.png","url":"https://assets-eu.researchsquare.com/files/rs-5358122/v1/d40ac4689a98d9281cf7d76c.png"},{"id":68746839,"identity":"1309b8da-d285-4142-815b-dc94c7c6393d","added_by":"auto","created_at":"2024-11-11 15:28:45","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":7757913,"visible":true,"origin":"","legend":"\u003cp\u003ePercentage of isolates by point with potential phosphate solubilization activity.\u003c/p\u003e","description":"","filename":"Fig.3.png","url":"https://assets-eu.researchsquare.com/files/rs-5358122/v1/72dee7bfc670b637da980231.png"},{"id":68746835,"identity":"d8d19145-b839-4c10-b1e0-7bc22e2a7fbe","added_by":"auto","created_at":"2024-11-11 15:28:44","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":1409822,"visible":true,"origin":"","legend":"\u003cp\u003eNeighbour-joining tree showing the phylogenetic positions of strains ANTART 23, 34, 36, 46, 66 and 76 with other closely related members based on 16 S rRNA gene sequences available from the Genbank database (accession numbers are given in parentheses).\u003c/p\u003e","description":"","filename":"Fig.4.png","url":"https://assets-eu.researchsquare.com/files/rs-5358122/v1/f521a7ef1737d13d1560925e.png"},{"id":68746838,"identity":"1c5d1509-6f7f-44ab-80d8-6a6cc045b263","added_by":"auto","created_at":"2024-11-11 15:28:44","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":158163,"visible":true,"origin":"","legend":"\u003cp\u003ePrincipal component analysis of phosphate solubilizers activity evaluation. Half Moon Island, Antarctica.\u003c/p\u003e","description":"","filename":"Fig.5.png","url":"https://assets-eu.researchsquare.com/files/rs-5358122/v1/cb03094214fccb14a43cb768.png"},{"id":74858388,"identity":"59a75fed-f267-4cc9-9ad5-240b5f2e4d17","added_by":"auto","created_at":"2025-01-27 16:08:51","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":15043166,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5358122/v1/be4fd519-e372-44c6-9ce7-720931628897.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Phosphate Solubilization by Microorganisms in Pyroclastic Material from Half Moon Island in Antarctica: Implications for Astrobiology","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eHistorically, Mars has captivated the scientific community and is considered a planetary body with potential for looking for life outside the Earth, as well as a terrestrial planet with similar ancient conditions to promote the emergence of life on its early geological stages (Camprub\u0026iacute; et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). This hypothesis stems from the discovery of various microorganisms inhabiting extreme environments on Earth, considered analogs of Mars (Joseph et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). One such place is Antarctica, where three Martian analogs have been identified: Dry Valleys, North Victoria Land Mountains, and Lake Vostok. These regions share extreme conditions, including low temperatures, strong winds, permafrost, and isolation (Anderson et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e1972\u003c/span\u003e; Mee\u0026szlig;en et al., \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Martins et al., \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2017\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThese analogs allow us to understand various aspects of the planetary body to which the analogy is drawn. Some terrestrial analogs facilitate understanding of planetary processes, mineralogy, and even the different adaptations that life might develop in such physiologically stressful environments (Foucher et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). On the other hand, in several regions of Antarctica, such as the South Shetland Islands, the phosphorus cycle is poorly understood. In other areas, like the McMurdo Dry Valleys, it is known that tills (poorly sorted, unstratified glacial deposits) represent the largest phosphorus reserves, although transport rates have not been quantified (Bate et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Zeglin et al., \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2009\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe global phosphorus cycle and its interactions play a fundamental role in climate modeling and landscape formation (Xu et al., \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). Phosphorus is an essential component in all known life forms on our planet due to its role in biomolecules such as DNA, phospholipids, and ATP, among others (Sylvia et al., \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2005\u003c/span\u003e). There are two main sources that supply phosphate: 1) guano, formed from bird excrement, and 2) apatite, rocks with high concentrations of calcium phosphate (Fillippelli \u0026amp; Souch, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e1999\u003c/span\u003e; Bate et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2008\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe phosphorus cycle is often influenced by the composition of parent material and in situ rates of processes, including weathering, biological uptake, and cycling. Since phosphorus is affected by both biological and chemical reactions, a straightforward way to understand these interactions is to divide the phosphorus cycle into two sub-cycles: 1) geochemical and 2) biological. In the geochemical sub-cycle, minerals are solubilized into orthophosphate through chemical and biochemical weathering processes. The release of orthophosphate into soil solution, which is subsequently absorbed by plants and microorganisms, occurs through the dissolution of compounds by microbiologically produced organic acids (Smeck, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e1985\u003c/span\u003e; Sylvia et al., \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2005\u003c/span\u003e). In the biological sub-cycle, orthophosphate is either stored by plants or immobilized by microbial biomass. Plant and/or animal waste reincorporates organic phosphorus into the soil in three different ways: i) stable humus, ii) as mineralized orthophosphate, or iii) as immobilized microbial biomass. Phosphorus from biomass is also incorporated into humic substances, mineralization, and immobilization reactions (Bate et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Zheng et al., \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eOn Half Moon Island, very little is known about microbiology, and considering that nutrient mobilization in Antarctica is largely due to microorganisms, their relationship with nutrient cycling, specifically the phosphorus cycle, is also unknown. This study aims to evaluate the capacity of microorganisms present in the pyroclastic material of Half Moon Island to solubilize phosphates and their relevance to astrobiological studies on Mars.\u003c/p\u003e"},{"header":"2. Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1. Study Area, Sample Collection, and Mapping\u003c/h2\u003e \u003cp\u003eThe samples were collected on Half Moon Island (S 62\u0026deg; 35\u0026rsquo;; W 59\u0026deg; 55\u0026rsquo;), South Shetland Islands, in the northern region of the Antarctic Peninsula, between Drake Passage and Bransfield Sea (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA), during the Antarctic summer of 2015\u0026ndash;2016, specifically in February. During the sample collection, the average air temperature was 0.609\u0026deg;C, with an ambient humidity of 93.648%, solar radiation of 130.175 W/m\u0026sup2;, wind speed of 32.564 km/h, and atmospheric pressure of 981.272 hPa, according to data from the oceanographic sailing vessel Bernardo Houssay, operated by The Argentine Naval Prefecture, anchored in Moon Bay.\u003c/p\u003e \u003cp\u003eSampling was conducted in a Z-pattern across the island, at five different points where sediment remained frozen for most of the year and located away from areas heavily impacted by humans, to ensure the presence of native microbiota (sampling points P1, P2, P3, P4, P5) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eB). Additionally, a control sample was taken from an area with a snow or ice layer and significant human intervention, selecting a penguin colony due to the high influx of tourists (sampling point P6) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eB). At each point, an individual sediment sample was collected from a depth of 2 to 15 cm, placed in sterile bags, and preserved in cold conditions until transported to the laboratory (4\u0026deg;C).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Physicochemical Analysis of Sediments\u003c/h2\u003e \u003cp\u003eThe sediment samples were analyzed to determine various characteristics, focusing on parameters relevant to sediment studies, including pH and elemental content (P, Ca, N, S). The Bray II method was used for phosphorus extraction, which involves the use of ammonium fluoride in dilute hydrochloric acid (Garc\u0026iacute;a \u0026amp; Ballesteros, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). The Walkley-Black method was employed to determine organic carbon, which involves the wet oxidation of the soil sample using potassium dichromate solution. From this, easily oxidizable carbon was calculated, and the total organic carbon percentage was derived using a variable correction factor (Eyherabide et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). The nitrogen content was calculated based on the percentage of organic carbon, using a standardized formula that includes the nitrogen mineralization constant according to climate conditions and the nitrogen availability factor based on soil texture (Brust, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). This analysis was performed using atomic absorption spectrometry following extraction with 1N ammonium acetate at pH 7. The sulfur content was quantified using a turbidimetric method, while the pH was determined using a saturation paste and a potentiometer.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Culture of Microorganisms\u003c/h2\u003e \u003cp\u003eMicroorganism isolations were conducted using the methodology established by Harrigan and McCance (Harrigan \u0026amp; McCance, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e1966\u003c/span\u003e). Starting from a mother solution with 10 g of sediment from each sampling point in 90 mL of sterile saline solution (0.9% NaCl), dilution series were performed from 10⁻\u0026sup1; to 10⁻⁹ with saline solution, plating onto nutrient agar and incubating at 15\u0026deg;C, in triplicate until growth was observed. After obtaining the plating results, countable dilutions (between 30 and 300 CFU/g according to the standard method) were selected (Madigan \u0026amp; Martino, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2006\u003c/span\u003e), and subcultures were made in nutrient agar for isolation, followed by Gram staining to verify purity. In cases of impure isolates, successive subcultures were performed. Once obtained, the cultures were incubated at 15\u0026deg;C.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Assessment of phosphate-solubilizing activity in bacteria.\u003c/h2\u003e \u003cp\u003eTo evaluate the inorganic phosphate-solubilizing bacteria, SRS medium was used (0.5 g/L (NH\u003csub\u003e4\u003c/sub\u003e)2SO\u003csub\u003e4\u003c/sub\u003e; 0.2 g KCl; 0.3 g/L MgSO\u003csub\u003e4\u003c/sub\u003e; 0.01 g/L MnSO\u003csub\u003e4\u003c/sub\u003e; 0.01 g/L FeSO\u003csub\u003e4\u003c/sub\u003e; 0.2 g/L NaCl; 10 g/L glucose; 0.5 g/L yeast extract; 18 g/L agar-agar, distilled water). Bromocresol purple was added, and the pH was adjusted to 7.0-7.5, according to the IGAC protocol (2006). From the isolated colonies, a mass inoculation was performed in the SRS medium containing calcium phosphate salts and bromocresol purple as a pH indicator. After 24 to 48 hours at 15\u0026deg;C, bacterial colonies that acidified the culture medium (color change from purple to yellow) and/or formed a transparent halo around the colony, indicating the production of tricalcium phosphate or solubilizing activity due to presumed enzymatic activity, were identified as positive.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.5 Identification of microorganisms\u003c/h2\u003e \u003cp\u003eGenomic DNA was extracted from the strains that presented transparent or yellow halos greater than 15 mm in SRS medium, using the ZR Fungal / Bacterial DNA MiniPrep kit (Zymo Research, USA). The 16S rRNA gene was amplified by PCR under the following conditions (50 \u0026micro;L): 1X Taq polymerase buffer, 1.5 mM MgCl2, 0.2 mM dNTPs, 0.4 \u0026micro;M forward primer 27F (5\u0026rsquo;-AGAGTTTGATCCTGGCTCAG-3\u0026rsquo;), 0.4 \u0026micro;M reverse primer 1492R (5\u0026rsquo;-GGTTACCTTGTTACGACTT-3\u0026rsquo;), 1.25 U of Taq DNA polymerase GoTaq\u0026reg; Flexi DNA Polymerase (Promega), and 10\u0026ndash;100 ng of genomic DNA. The PCR was conducted in a thermocycler (Mastercycler Pro, Eppendorf AG) with the following program: 2 min at 95\u0026deg;C; 30 cycles of 20 s at 94\u0026deg;C, 20 s at 50\u0026deg;C, and 90 s at 72\u0026deg;C; and 10 min at 72\u0026deg;C. The PCR products were sequenced using Sanger sequencing on the ABI 3500 capillary electrophoresis system. The 16S rRNA sequences were compared in GenBank. Multiple alignments of different 16S rRNA sequences of bacteria related to cold environments from the GenBank database were performed using Highly similar sequences (megablast). Phylogenetic analysis was conducted using MEGA 11 software. Unrooted trees were constructed using the Maximum Parsimony method. A bootstrap analysis of 1000 iterations was performed with the dataset.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.5 Determination of acid and alkaline phosphatase activity (EC 3.1.3.2 and 3.1.3.1, respectively) in sediments.\u003c/h2\u003e \u003cp\u003eThe p-nitrophenol released after incubating sediment samples with p-nitrophenyl phosphate (PNP) solution for 1 hour at 37\u0026deg;C was determined (Alef \u0026amp; Nannipieri, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1995\u003c/span\u003e). The p-nitrophenol released by the activity of phosphomonoesterase was extracted and colored In a solution of 1.21g of Tris, 1.16g of malic acid, 1g of monohydrated citric acid, and 0.63g of boric acid in 100mL of 1M NaOH. (Adjusted with HCl to pH 6.5 for acid phosphatase and with NaOH to pH 11 for alkaline phosphatase), and finally, photometrically measured at 400 nm, according to the standardized procedure by Avellaneda (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2008\u003c/span\u003e) following the protocols of Tabatabai \u0026amp; Bremner (\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e1969\u003c/span\u003e) and Eivazi \u0026amp; Tabatabai (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e1977\u003c/span\u003e). This procedure was performed on five subsamples for each sampling point and three replicates for each subsample. Subsequently, the mean of the replicates per subsample and the mean of the subsamples were calculated, yielding a unique value per point.\u003c/p\u003e \u003cp\u003eBased on the unique absorbance values obtained for each sample and the respective controls, and using the previously determined equation of the line for the calibration curve, the \u0026micro;g PNP \u0026middot; ml⁻\u0026sup1; were calculated. These were then introduced into the equation presented below to calculate the enzymatic activity expressed as \u0026micro;g PNP \u0026middot; g⁻\u0026sup1; dm \u0026middot; h⁻\u0026sup1; (Avellaneda, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2008\u003c/span\u003e).\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:\\mu\\:g\\:pNP*{g}^{-1}dm*{h}^{-1}=\\frac{\\left(S-C\\right)*F*V*100}{W*\\%dm*t}$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWhere,\u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(\\:S\\)\u003c/span\u003e \u003c/span\u003e = Average value of the samples (\u0026micro;g pNP*mL-1)\u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(\\:C\\)\u003c/span\u003e \u003c/span\u003e = Control (\u0026micro;g pNP *mL-1)\u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(\\:V\\)\u003c/span\u003e \u003c/span\u003e = Volume of the extract (mL)\u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(\\:W\\)\u003c/span\u003e \u003c/span\u003e = Sediment (henceforth called soil) initial weight\u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(\\:{100*\\%}^{-1}dm\\)\u003c/span\u003e \u003c/span\u003e = dry soil weight factor = dwt \u0026oacute; Dry weight of 1g of soil\u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(\\:t\\)\u003c/span\u003e \u003c/span\u003e = incubation time (h)\u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(\\:F\\)\u003c/span\u003e \u003c/span\u003e = dilution factor\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e2.6 Statistical analysis\u003c/h2\u003e \u003cp\u003eFor the statistical analysis, the free software R Commander was used. Principal Component Analysis (PCA) was performed on the data from the physicochemical sediment analysis, phosphatase enzyme activity, and phosphate-solubilizing microbial populations to determine the correlations between the studied variables, establish patterns, and attempt to reduce the number of variables.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e3.1. Physicochemical Analysis of Sediments\u003c/h2\u003e \u003cp\u003eResults from sediment analysis are presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Textural analyses were not considered, given that these classifications apply to formed soils, while the collected samples correspond to highly weathered pyroclasts that have not yet developed a soil matrix; thus, a textural classification would be inaccurate.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eResults of physicochemical analysis of sediments collected on Half Moon Island, Antarctica\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"10\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSampling point\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003epH\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eP (mg/Kg)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eC (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eN (Kg/ha)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eK (mg/Kg)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eFe (mg/Kg)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eMg (mg/Kg)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eCa(mg/Kg)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003eS (mg/Kg)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e245.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.49%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e8.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e206.87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e274\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e598\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e39.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2100.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.78%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e13.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e180.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e494\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e184\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e2280\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e497.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.64%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e11.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e148.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e355\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e121.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e1422\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e21.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6.77\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e701.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.49%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e8.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e121.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e518.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e97.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e430\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e7.40\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5.76\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e284.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.39%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e6.70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e66.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e564\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e56.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e256\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3156.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.76%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e13.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e429\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e824\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e440\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e9.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Culture of microorganisms\u003c/h2\u003e \u003cp\u003eThe cultivation plates incubated at 15\u0026deg;C showed observable growth between 24 and 72 hours after inoculation. Countable growth was present in the 10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e and 10\u003csup\u003e\u0026minus;\u0026thinsp;6\u003c/sup\u003e dilutions, except for point P5, where countable colonies were observed even at a dilution of 10\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e. In dilutions lower than 10\u003csup\u003e\u0026minus;\u0026thinsp;6\u003c/sup\u003e, growth was insignificant. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e presents the counts of purified isolates across samples.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Qualitative assessment of phosphate solubilizing activity\u003c/h2\u003e \u003cp\u003eThe obtained isolates were subsequently evaluated in SRS medium. The percentage of positive growth for potential phosphate solubilization activity (Ca\u003csub\u003e3\u003c/sub\u003e(PO\u003csub\u003e4\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e) by sampling point is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Identification of microorganisms\u003c/h2\u003e \u003cp\u003eConsidering the established parameters, six isolates were analyzed using the 16S gene, identifying them as related to \u003cem\u003ePseudomonas yamanorum\u003c/em\u003e, \u003cem\u003ePseudomonas canavaninivorans\u003c/em\u003e, and \u003cem\u003ePseudomonas libanensis\u003c/em\u003e, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003e3.5 Determination of Acid and Alkaline Phosphatase Activity\u003c/h2\u003e \u003cp\u003eThe enzyme activity by sampling point is presented in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePhosphatase activity by sampling point. Half Moon Island, Antarctica.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSampling point\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAcid phosphatase (\u0026micro;g PNP/g dry soil*hour)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAlkaline phosphatase (\u0026micro;g PNP/g dry soil*hour)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.27\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.41\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3.92\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6.57\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.99\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e9.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5.40\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003e3.6 Statistical analysis\u003c/h2\u003e \u003cp\u003eAccording to the principal component analysis, the integrated graph of components 1 and 2 was generated, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e. The first two components were selected because they explain 86.7% of the presented variables. Potential activity of phosphate solubilizing bacteria is indicated by the blue dotted arrow. The different chemical elements, acid and alkaline phosphatase, and each sampling point are presented.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eAccording to Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, it is possible to see that the points with the highest phosphorus content are P6 and P2, respectively. P6 corresponds to the penguin colony, a site highly impacted by tourist influence, as well as by the presence of a colony of Gentoo penguins (\u003cem\u003ePygoscelis antarcticus\u003c/em\u003e), whose diet primarily consists of fish, krill, and small crustaceans (Lynnes, Reid, \u0026amp; Croxall, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2004\u003c/span\u003e). On the other hand, P2 is a sample from the Caleta Menguante beach area, composed of rock fragments. These sediment compositions preliminarily align with what Bate and colleagues (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2008\u003c/span\u003e) described, with a greater presence of guano and rock. Although due to its phosphorus content it cannot be classified as phosphorite (since its P\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e content is less than 4%), its content is significant compared to the other sampling points. Another noteworthy parameter is the pH variation in the contrasting sample P6, where the presence of acidic guano alters the physicochemical properties of the pyroclast (Bate et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Hopkins et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2008\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe potential activity of phosphate-solubilizing bacteria (based on isolate counts), it was observed that a high percentage exhibited, except for sampling point P5, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. Additionally, Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e indicates that the potential solubilizing activity (blue dotted arrow) is completely independent of the phosphorus content in the sediments; instead, a direct relationship was observed with the sulfur and magnesium content, but especially with the calcium content. These results are also like those reported by Bate and colleagues (Bate et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2008\u003c/span\u003e), where the presence of phosphorus in some Antarctic environments is related to its affinity for calcium (Ca) fractions. Interestingly, an inverse correlation was observed between potential solubilizing activity and acid phosphatase activity. A similar relationship was observed with alkaline phosphatase activity and iron content. This behavior may be explained by competitive interactions, as microbial competition in polar soil has been reported to be intensified due the limited access to soil nutrients and space, a dynamic that may be increased during summer (Bell et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). Bertk Pinto et al, (2019) reported a strong correlation between bacterial competition and organic acid contractions in arctic snow, where a higher number of bacterial taxa were associated with higher organic acid levels. This relationship is notable, as organic acids are produced in the phosphate solubilization (Corrales et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2014\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFurthermore, low rates of biological mobilization were found due to the present immobilization and nutrient transformation (Bate et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). This is likely due to biotic factors responsible for the dynamics of the elements, and the abiotic component responsible for the spatial and temporal variability of the phosphate gradients present in Antarctic soils, as the relationship of solubilizing microorganisms with calcium would indicate this P-Ca relationship in the immobilization of the element in Antarctic sediments. This is understandable considering that among the types of inorganic phosphorus used by solubilizing microorganisms are fluorapatite, hydroxyapatite, and tricalcium phosphate, all of which contain calcium in their structure. One of the pathways for phosphorus solubilization is the production of organic acids, which acidify the medium and facilitate phosphorus availability; as they carry negative charges, they can chelate metal ions such as Ca\u0026sup2;⁺ and release phosphorus (Corrales et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). This production of organic acids was evidenced in most isolates, indicated by a yellow coloration in the medium due to a shift in the pH indicator (bromocresol purple), which allows us to infer that this would be the most utilized mechanism for phosphorus solubilization, and it would be defined by the calcium content.\u003c/p\u003e \u003cp\u003eRegarding phosphatase activity, no relationship was observed between alkaline phosphatase activity and the percentage of microorganisms with solubilizing activity. In contrast, acid phosphatase activity showed a slightly negative relationship with solubilizing activity (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e), considering the orthogonality of the two variables as a function of component 1 and 2. This may be because phosphatase participates in the glucose cycle, facilitating phosphorus solubilization, as this mechanism of periplasmic oxidation of glucose to gluconic acid has been predominantly evidenced in Gram-negative bacteria (Beltr\u0026aacute;n, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2014\u003c/span\u003e), such as the genus Pseudomonas. Furthermore, cultivable microorganisms represent only between 0.1% and 1% of the total microbial population present in the soil (Reeder \u0026amp; Knight, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2009\u003c/span\u003e), so the recorded activity could correspond to microorganisms that are non-viable under laboratory conditions. On the other hand, alkaline and acid phosphatase activity is indeed very low compared to soils with agricultural crop activity; for example, in a soil with soybean cultivation, activities range from 5.72 to 15.5 \u0026micro;g PNP g⁻\u0026sup1; soil h⁻\u0026sup1; for alkaline phosphatase and from 27.4 to 105 \u0026micro;g PNP g⁻\u0026sup1; soil h⁻\u0026sup1; for acid phosphatase (Fern\u0026aacute;ndez et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2008\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn the evaluated sediments, the highest value for acid phosphatase corresponded to 9.20 \u0026micro;g PNP g⁻\u0026sup1; soil h⁻\u0026sup1; and 5.40 \u0026micro;g PNP g⁻\u0026sup1; soil h⁻\u0026sup1; for alkaline phosphatase at the control point P6, where there is animal activity. In contrast, the lowest value was recorded at 0.30 \u0026micro;g PNP g⁻\u0026sup1; soil h⁻\u0026sup1; for acid phosphatase at points P1 and P2, and 0.41 \u0026micro;g PNP g⁻\u0026sup1; sediment h⁻\u0026sup1; for alkaline phosphatase at P3. Temperature plays a fundamental role in enzyme activity, as lower than optimal temperatures result in decreased metabolism for its production, with phosphatase typically showing its optimum activity at temperatures close to 37\u0026deg;C (Blanco, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e1992\u003c/span\u003e). The low production of these enzymes is supported by the slow growth rate of the psychrophilic microorganisms that could produce it (Feller and Gerday, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2003\u003c/span\u003e; Buford \u0026amp; Sowers, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2004\u003c/span\u003e, Fanin et al., \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe presence of phosphate-solubilizing microorganisms in extreme environments, such as Half Moon Island in Antarctica, is not only crucial for understanding biogeochemical cycles in these ecosystems but also has significant implications for the search for biosignatures on Mars (Berenjian \u0026amp; Seifan, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). The ability of these microorganisms to release phosphorus from insoluble inorganic compounds into forms available for other organisms could be fundamental for the sustainability of life under extreme conditions, both on Earth and potentially on other planets (Plante, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Tian et al., \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Silva et al., \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). At Half Moon Island, an environment characterized by extreme temperature conditions and high solar radiation, phosphate-solubilizing microorganisms play a crucial role in the availability of this essential nutrient for life. The results obtained in this study indicate that several sampling points on the island showed significant activity of these microorganisms, as evidenced by the presence of specific bioindicators and their ability to acidify the medium, thereby facilitating phosphorus release (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e; Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe relevance of these findings extends beyond Antarctica, as the ability of microorganisms to solubilize phosphate could have direct implications for Mars exploration (R\u0026ouml;ling et al., \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Hausrath et al., \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). The presence of phosphates in Martian soil has been well documented by missions such as the Mars Rover Curiosity (Grotzinger et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Grotzinger et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2015\u003c/span\u003e), suggesting that this key element for life may be present in inorganic forms that could be accessible to phosphate-solubilizing microorganisms. The detection of enzymatic activities such as acid and alkaline phosphatase in Antarctic sediments provides a useful model for understanding how these microorganisms might behave in similar Martian environments, where extreme conditions could also promote processes of solubilization of essential nutrients for microbial life (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFurthermore, the association between phosphate solubilizing activity and other elements such as calcium, sulfur, and magnesium in the sediments of Half Moon Island suggests possible complex biochemical interactions (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e) that could be explored as potential biosignatures on Mars. The ability of microorganisms to modify soil chemistry and release essential nutrients could leave specific geochemical markers, detectable through spectroscopy techniques and advanced microscopic analyses in future space exploration missions.\u003c/p\u003e \u003cp\u003eFinally, another fundamental aspect in the field of astrobiology is that these types of microorganisms facilitate the mobilization of nutrients to plants. This is why organisms tolerant to low temperatures and other adverse conditions, such as those present in Antarctica, and capable of solubilizing phosphates, could promote plant growth in future manned missions to Mars, ensuring the use of in situ substrates.\u003c/p\u003e"},{"header":"5. Conclusions and Perspectives","content":"\u003cp\u003eThe research on microorganisms with phosphate solubilizing activity in Half Moon Island has provided valuable insights into their role in the phosphorus cycle and their interaction with the Antarctic environment. Below are the conclusions derived from the findings and the future perspectives that arise from this study. These conclusions not only highlight the relevance of these microorganisms in local ecosystems but also suggest lines of research that may contribute to our understanding of life in extreme conditions, both on Earth and on other celestial bodies, such as Mars.\u003c/p\u003e \u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003e5.1 Conclusions\u003c/h2\u003e \u003cp\u003e \u003col\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eMicrobial Activity and the Phosphorus Cycle: The culturable microorganisms identified in Half Moon Island exhibit phosphate solubilization activity, indicating their capacity to significantly contribute to the mineralization and mobilization of phosphorus in this Antarctic environment. This activity suggests that these microorganisms are fundamental to soil biochemistry and may influence the availability of nutrients for other forms of life.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eRelationship with Chemical Elements: The phosphate solubilization activity in microbial communities may be related to the abundance of other chemical elements in the sediments of Half Moon Island. This suggests the existence of complex biogeochemical networks in which these microorganisms play a crucial role in nutrient interaction and availability.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eInfluence of Temperature: It was observed that temperature directly affects the growth rate of microorganisms and their production of phosphatases. This highlights the importance of climatic conditions in microbial dynamics and their ability to solubilize phosphorus, which is relevant in the context of climate change and its effects on Antarctic ecosystems.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eComparison with Other Antarctic Regions: The phosphorus and calcium dynamics observed in Half Moon Island are consistent with those recorded in other areas of the Antarctic Peninsula, suggesting patterns of microbial activity that may be common across various locations on the continent.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003c/ol\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003e5.2 Perspectives\u003c/h2\u003e \u003cp\u003e \u003col\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eFuture Studies on Ecological Interactions: Further research is recommended to assess how microorganisms with phosphate solubilization activity interact with plant dynamics in Half Moon Island. Since these microorganisms are crucial for soil formation, studying them will provide better insights into ecosystems and their resilience in extreme environments.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eAstrobiological Conditions: It is crucial to explore the dynamics of these microorganisms under astrobiological interest conditions, particularly those simulating Martian environments. This may provide valuable information regarding the possibility of microbial life in the past or present on that planet, as well as the potential for these microorganisms to adapt and thrive in extraterrestrial conditions.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eImplications for Space Missions: Identifying microorganisms capable of phosphate solubilization on Mars should be a serious goal for future space missions. These organisms could not only indicate past conditions conducive to life but could also be used in terraforming strategies or in nutrient production to sustain future crewed missions.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003c/ol\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e\u003ch2\u003eConflict of interest:\u003c/h2\u003e \u003cp\u003eThe authors declare that they have no conflicts of interest.\u003c/p\u003e\u003ch2\u003eFunding:\u003c/h2\u003e \u003cp\u003eFor the integral development of the same has been supported and funded by counterparts of the authors\u0026rsquo; institutions.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eM.A.L. and D.T., were responsible for conceptualization; investigation; visualization; writing\u0026mdash;original draft, writing\u0026mdash;review and editing. A.I., O.B. and E.R. contributed to the investigation. J.S. and L.M.M. were in charge of conceptualization, resources, and supervision of the research.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThe authors would like to thank the institutions with which they work and collaborate since they are the ones that allow the development of the publication. Additionally, they extend special thanks to the Colombian Antarctic Program and the Argentine Navy for their constant collaboration in Antarctic research, especially in Camara Antarctic Station. Special thanks to the Planetario de Bogot\u0026aacute; for the award to the life and work of the science communicator in astronomy and space sciences, granted to the Astrobiology Science Club of the Universidad Nacional de Colombia on its ten-year anniversary in 2015, which was used to fund the research campaign for this study. We also extend our gratitude to the Universidad Nacional de Colombia for its constant support and for providing the laboratories and materials necessary for the laboratory phase of this work.\u003c/p\u003e\u003ch2\u003eAvailability of data and materials:\u003c/h2\u003e \u003cp\u003eAll the data generated or analyzed during this study are included in this published article.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAlef K, Nannipieri P (1995) Methods in Applied Soil Microbiology and Biochemistry. \u003cem\u003eAcademic Press\u003c/em\u003e, 311\u0026ndash;372\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAnderson D, Gatto L, Ugolii F (1972) An Antarctic analog of Martian permafrost terrain. 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Antarctica Environ Int 164:107228. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.envint.2022.107228\u003c/span\u003e\u003cspan address=\"10.1016/j.envint.2022.107228\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"polar-biology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pobi","sideBox":"Learn more about [Polar Biology](http://link.springer.com/journal/300)","snPcode":"300","submissionUrl":"https://submission.nature.com/new-submission/300/3","title":"Polar Biology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Phosphorus cycle, acid phosphatase, alkaline phosphatase, nutrient cycling","lastPublishedDoi":"10.21203/rs.3.rs-5358122/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5358122/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eMicroorganisms play a crucial role in the phosphorus cycle, as they mineralize and immobilize organic phosphorus and solubilize and precipitate the inorganic fraction of it. In various regions of the planet, the functional capacity of microorganisms in the solubilization process has been evaluated; however, in polar regions, the difficulty in accessing samples and handling microorganisms presents a limitation for understanding this cycle. This study aimed to evaluate the phosphate-solubilizing capacity of cultivable microorganisms present in volcanic soils of Half Moon Island in Antarctica and their astrobiological implications for Mars. Physicochemical soil analysis, traditional culture techniques, selective media cultivation, and enzymatic activity analysis for soil phosphatase were conducted. Growth of various isolates was observed across different sampling points, with phosphate-solubilizing activity ranging from 14.29\u0026ndash;92.31% of the isolates at each sampling point. These bacteria showed a direct relationship with soil calcium content. Phosphatase activity recorded low values, possibly affected by temperature and the low metabolic rate of in situ microorganisms. The findings suggest that microorganisms in Antarctic volcanic soils could contribute to astrobiological exploration on Mars.\u003c/p\u003e","manuscriptTitle":"Phosphate Solubilization by Microorganisms in Pyroclastic Material from Half Moon Island in Antarctica: Implications for Astrobiology","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-11-11 15:28:40","doi":"10.21203/rs.3.rs-5358122/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-11-26T10:43:05+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-11-13T17:52:27+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-11-12T07:02:49+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-11-11T14:58:34+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"330028744014022528123323662762476780997","date":"2024-11-05T15:12:27+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"252003811227491291749537939337278724559","date":"2024-11-04T16:06:46+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"78157887562638312384030293061535206374","date":"2024-11-02T19:22:04+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-11-02T18:27:50+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-10-30T16:44:49+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-10-30T09:09:32+00:00","index":"","fulltext":""},{"type":"submitted","content":"Polar Biology","date":"2024-10-30T04:06:16+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"polar-biology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pobi","sideBox":"Learn more about [Polar Biology](http://link.springer.com/journal/300)","snPcode":"300","submissionUrl":"https://submission.nature.com/new-submission/300/3","title":"Polar Biology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"a36d8c47-8e59-4b7a-95b0-d54558d2fa6a","owner":[],"postedDate":"November 11th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-01-27T16:01:22+00:00","versionOfRecord":{"articleIdentity":"rs-5358122","link":"https://doi.org/10.1007/s00300-025-03348-y","journal":{"identity":"polar-biology","isVorOnly":false,"title":"Polar Biology"},"publishedOn":"2025-01-23 15:57:30","publishedOnDateReadable":"January 23rd, 2025"},"versionCreatedAt":"2024-11-11 15:28:40","video":"","vorDoi":"10.1007/s00300-025-03348-y","vorDoiUrl":"https://doi.org/10.1007/s00300-025-03348-y","workflowStages":[]},"version":"v1","identity":"rs-5358122","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5358122","identity":"rs-5358122","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}