Articoli di riviste: "Microorganisms – Antarctica"

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González-Toril, E., R. Amils, R. J. Delmas, J. R. Petit, J. Komárek e J. Elster. "Diversity of bacteria producing pigmented colonies in aerosol, snow and soil samples from remote glacial areas (Antarctica, Alps and Andes)". Biogeosciences Discussions 5, n. 2 (15 aprile 2008): 1607–30. http://dx.doi.org/10.5194/bgd-5-1607-2008.

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Abstract. Four different communities and one culture of pigmented microbial assemblages were obtained by incubation in mineral medium of samples collected from high elevation snow in the Alps (Mt. Blanc area) and the Andes (Nevado Illimani summit, Bolivia), from Antarctic aerosol (French station Dumont d'Urville) and a maritime Antarctic soil (King George Island, South Shetlands, Uruguay Station Artigas). Molecular analysis of more than 200 16S rRNA gene sequences showed that all cultured cells belong to the Bacteria domain. The phylogenetic comparison with the currently available rDNA database allowed the identification of sequences belonging to Proteobacteria (Alpha-, Beta- and Gamma-proteobacteria), Actinobacteria and Bacteroidetes phyla. The Andes snow culture was the richest in bacterial diversity (eight microorganisms identified) and the maritime Antarctic soil the poorest (only one). Snow samples from Col du midi (Alps) and the Andes shared the highest number of identified microorganisms (Agrobacterium, Limnobacter, Aquiflexus and two uncultured Alphaproteobacteria clones). These two sampling sites also shared four sequences with the Antarctic aerosol sample (Limnobacter, Pseudonocardia and an uncultured Alphaproteobacteria clone). The only microorganism identified in the maritime Antarctica soil (Brevundimonas sp.) was also detected in the Antarctic aerosol. The two snow samples from the Alps only shared one common microorganism. Most of the identified microorganisms have been detected previously in cold environments (Dietzia kujamenisi, Pseudonocardia Antarctica, Hydrogenophaga palleronii and Brebundimonas sp.), marine sediments (Aquiflexus balticus, Pseudomonas pseudoalkaligenes, Pseudomonas sp. and one uncultured Alphaproteobacteria), and soils and rocks (Pseudonocardia sp., Agrobactrium sp., Limnobacter sp. and two uncultured Alphaproteobacetria clones). Air current dispersal is the best model to explain the presence of very specific microorganisms, like those used in this work, in very distant environments. In addition these microorganisms have to be resistant to extreme conditions and able to grow in oligotrophic environments. Considering the habitats in which they have been identified, the presence of pigments must be related with their ability to resist high doses of radiation.

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Sioma, I. B., V. M. Hovorukha e O. B. Tashyrev. "Mercury-resistant bacteria in Antarctic ecosystems". Faktori eksperimental'noi evolucii organizmiv 23 (9 settembre 2018): 381–86. http://dx.doi.org/10.7124/feeo.v23.1045.

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Aim. The research was focused on the assessment of the possible resistance of Antarctic microorganisms to mercury ions. Methods. Conventional microbiological methods of introducing of decimal dilutions to agar medium. Results. Microorganisms resistant to Hg2+ in high concentrations (up to 500 mg/l) were discovered among samples from Antarctica. The majority of Hg2+-resistant microorganisms was found in moss-lichen and soil ecosystems. The least of Hg2+-resistant microorganisms was found in organics-rich humus ecosystems. Conclusions. In Antarctic microbiocenoses were discovered for the first time microorganisms resistant to mercury in “bactericidal” concentrations in spite of absence of this element in the natural ecosystems. Apparently, the genome of these microorganisms contains genes that provide the mechanisms of microbial resistance to toxic mercury. Keywords: mercury, metal resistance, Antarctic microorganisms.

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Wong, Rasidnie Razin, Zheng Syuen Lim, Noor Azmi Shaharuddin, Azham Zulkharnain, Claudio Gomez-Fuentes e Siti Aqlima Ahmad. "Diesel in Antarctica and a Bibliometric Study on Its Indigenous Microorganisms as Remediation Agent". International Journal of Environmental Research and Public Health 18, n. 4 (5 febbraio 2021): 1512. http://dx.doi.org/10.3390/ijerph18041512.

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Diesel acts as a main energy source to complement human activities in Antarctica. However, the increased expedition in Antarctica has threatened the environment as well as its living organisms. While more efforts on the use of renewable energy are being done, most activities in Antarctica still depend heavily on the use of diesel. Diesel contaminants in their natural state are known to be persistent, complex and toxic. The low temperature in Antarctica worsens these issues, making pollutants more significantly toxic to their environment and indigenous organisms. A bibliometric analysis had demonstrated a gradual increase in the number of studies on the microbial hydrocarbon remediation in Antarctica over the year. It was also found that these studies were dominated by those that used bacteria as remediating agents, whereas very little focus was given on fungi and microalgae. This review presents a summary of the collective and past understanding to the current findings of Antarctic microbial enzymatic degradation of hydrocarbons as well as its genotypic adaptation to the extreme low temperature.

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González-Toril, E., R. Amils, R. J. Delmas, J. R. Petit, J. Komárek e J. Elster. "Bacterial diversity of autotrophic enriched cultures from remote, glacial Antarctic, Alpine and Andean aerosol, snow and soil samples". Biogeosciences 6, n. 1 (8 gennaio 2009): 33–44. http://dx.doi.org/10.5194/bg-6-33-2009.

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Abstract. Four different communities and one culture of autotrophic microbial assemblages were obtained by incubation of samples collected from high elevation snow in the Alps (Mt. Blanc area) and the Andes (Nevado Illimani summit, Bolivia), from Antarctic aerosol (French station Dumont d'Urville) and a maritime Antarctic soil (King George Island, South Shetlands, Uruguay Station Artigas), in a minimal mineral (oligotrophic) media. Molecular analysis of more than 200 16S rRNA gene sequences showed that all cultured cells belong to the Bacteria domain. Phylogenetic comparison with the currently available rDNA database allowed sequences belonging to Proteobacteria Alpha-, Beta- and Gamma-proteobacteria), Actinobacteria and Bacteroidetes phyla to be identified. The Andes snow culture was the richest in bacterial diversity (eight microorganisms identified) and the marine Antarctic soil the poorest (only one). Snow samples from Col du Midi (Alps) and the Andes shared the highest number of identified microorganisms (Agrobacterium, Limnobacter, Aquiflexus and two uncultured Alphaproteobacteria clones). These two sampling sites also shared four sequences with the Antarctic aerosol sample (Limnobacter, Pseudonocardia and an uncultured Alphaproteobacteriaclone). The only microorganism identified in the Antarctica soil (Brevundimonas sp.) was also detected in the Antarctic aerosol. Most of the identified microorganisms had been detected previously in cold environments, marine sediments soils and rocks. Air current dispersal is the best model to explain the presence of very specific microorganisms, like those identified in this work, in environments very distant and very different from each other.

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Pearce, David A., Paul D. Bridge, Kevin A. Hughes, Birgit Sattler, Roland Psenner e Nick J. Russell. "Microorganisms in the atmosphere over Antarctica". FEMS Microbiology Ecology 69, n. 2 (agosto 2009): 143–57. http://dx.doi.org/10.1111/j.1574-6941.2009.00706.x.

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Monsalves, María T., Gabriela P. Ollivet-Besson, Maximiliano J. Amenabar e Jenny M. Blamey. "Isolation of a Psychrotolerant and UV-C-Resistant Bacterium from Elephant Island, Antarctica with a Highly Thermoactive and Thermostable Catalase". Microorganisms 8, n. 1 (10 gennaio 2020): 95. http://dx.doi.org/10.3390/microorganisms8010095.

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Microorganisms present in Antarctica have to deal not only with cold temperatures but also with other environmental conditions, such as high UV radiation, that trigger the generation of reactive oxygen species. Therefore, Antarctic microorganisms must have an important antioxidant defense system to prevent oxidative damage. One of these defenses are antioxidant enzymes, such as catalase, which is involved in the detoxification of hydrogen peroxide produced under oxidative conditions. Here, we reported the isolation and partial characterization of an Antarctic bacterium belonging to the Serratia genus that was resistant to UV-C radiation and well-adapted to cold temperatures. This microorganism, denominated strain I1P, was efficient at decreasing reactive oxygen species levels produced after UV-C irradiation. Genomic and activity assays suggested that the enzymatic antioxidant defense mechanisms of strain I1P, especially its catalase enzyme, may confer UV resistance. This catalase was active in a wide range of temperatures (20–70 °C), showing optimal activity at 50 °C (at pH 7.0), a remarkable finding considering its psychrotolerant origin. In addition, this enzyme was thermostable, retaining around 60% of its activity after 6 h of incubation at 50 °C. The antioxidant defense systems of strain I1P, including its surprisingly thermoactive and thermostable catalase enzyme, make this microorganism a good source of biocompounds with potential biotechnological applications.

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Nakai, Ryosuke, Eri Shibuya, Ana Justel, Eugenio Rico, Antonio Quesada, Fumihisa Kobayashi, Yasunobu Iwasaka et al. "Phylogeographic analysis of filterable bacteria with special reference toRhizobialesstrains that occur in cryospheric habitats". Antarctic Science 25, n. 2 (20 marzo 2013): 219–28. http://dx.doi.org/10.1017/s0954102012000831.

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AbstractAlthough the lower size limit of microorganisms was previously believed to bec. 0.2 μm, there is evidence for the existence of microorganisms that can pass through 0.2 μm-pore-size filters called ultramicrobacteria or nanobacteria. However, information on the phylogeny and biogeography of these bacteria is limited. We obtained 53 isolates of 0.2 μm-passable bacteria from 31 samples collected at 26 locations worldwide, including the Arctic Svalbard Islands, deserts, and Maritime Antarctica. Phylogenetic analysis of near full-length 16S rRNA gene sequences revealed that 18 of the 53 isolates were < 97% homologous with previously cultured isolates, representing potentially novel species. Two isolates (orderRhizobiales) (100% identical) collected from Byers Peninsula, Livingston Island in Maritime Antarctica, were closely related (99.8% similarity) to an isolate collected from intertidal sediments in East Antarctica. In addition, the sequence of this Antarctic isolate showed ≥ 97% similarity to 901 sequences derived from known isolates and samples collected at geographically disparate locations under various environmental conditions. Interestingly, among 13 sequences showing ≥ 99% similarity, ten were isolated from cryospheric habitats such as Arctic, Antarctic, and alpine environments. This implies that suchRhizobialesstrains occur in the cryospheric regions, however, their abundance and biomass may be scarce depending on the geographic location.

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Žákovská, Alena, Olivie Zezulová e Kristián Brat. "Changes in immunological and physiological parameters in urine duringAntarctic Scientific Expedition( Short Communication )". Czech Polar Reports 5, n. 1 (1 gennaio 2015): 69–74. http://dx.doi.org/10.5817/cpr2015-1-7.

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The aim of this study was to examine the effect of extreme climatic conditions on certain immunological and physiological parameters in urine in participants of the 9th Czech Antarctic Scientific Expedition, January – February 2015. The studied parameters were pH, number of leukocytes in 1 µl urine and the amount of proteins, nitrites, blood and haemoglobin in urine. A total of 45 urine samples were collected during 3 series of sampling (first pre-departure, second during the first 2 weeks of the stay in Antarctica, and third in the last 2 weeks of the stay). Paired t-test was used for comparison of the data from the Czech Republic and the Antarctica. We have found statistically significant decreases in pH and in the number of leukocytes in urine during the stay in Antarctica. The other parameters showed no changes. We conclude that several factors of the Antarctic environment (with lack of stress, pathogenic microorganisms and pollutants) may have positive effects on certain aspects of human health, and discuss the likely causes and mechanisms.

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Martins, César de Castro, Rosalinda Carmela Montone, Rosa Carvalho Gamba e Vivian Helena Pellizari. "Sterols and fecal indicator microorganisms in sediments from Admiralty Bay, Antarctica". Brazilian Journal of Oceanography 53, n. 1-2 (giugno 2005): 1–12. http://dx.doi.org/10.1590/s1679-87592005000100001.

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Sediments from the proximity of Ferraz station outfall, located in Admiralty Bay, Antarctica, were analyzed for fecal indicator microorganisms and sterols during the austral summer of 1999/2000 in order to assess human sewage input. Concentrations of total sterols and coprostanol ranged from 0.09 to 19.6 ¼g.g-1 and < 0.01 and 14.0 ¼g.g-1 dry weight (dw), respectively. Our analyses indicated that only sites within to 400m of the sewage outfall exhibited a sterol signal characteristic of human sewage input. Low levels of coprostanol and high levels of cholesterol in distant sites could be attributed to natural sources such as marine mammals and planktonic organisms. Fecal indicator microorganisms (E. coli, fecal streptococci and Clostridium perfringens) were non-detectable beyond 50m from outfall. Both indicators (sterols and fecal indicator microorganisms) produced consistent data and fecal sterol parameters have sho wn themselves to be efficient in the evaluation of trace amounts of fecal material. This study concluded that sewage contamination is limited to the immediate vicinity of the sewage outfall. In general, the concentration of fecal sterols and microbiological indicators were lower than in other Antarctic areas.

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Boenigk, Jens, Karin Pfandl, Tobias Garstecki, Hauke Harms, Gianfranco Novarino e Antonis Chatzinotas. "Evidence for Geographic Isolation and Signs of Endemism within a Protistan Morphospecies". Applied and Environmental Microbiology 72, n. 8 (agosto 2006): 5159–64. http://dx.doi.org/10.1128/aem.00601-06.

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ABSTRACT The possible existence of endemism among microorganisms resulting from and preserved by geographic isolation is one of the most controversial topics in microbial ecology. We isolated 31 strains of “Spumella-like” flagellates from remote sampling sites from all continents, including Antarctica. These and another 23 isolates from a former study were characterized morphologically and by small-subunit rRNA gene sequence analysis and tested for the maximum temperature tolerance. Only a minority of the Spumella morpho- and phylotypes from the geographically isolated Antarctic continent follow the worldwide trend of a linear correlation between ambient (air) temperature during strain isolation and heat tolerance of the isolates. A high percentage of the Antarctic isolates, but none of the isolates from locations on all other continents, were obligate psychrophilic, although some of the latter were isolated at low ambient temperatures. The drastic deviation of Antarctic representatives of Spumella from the global trend of temperature adaptation of this morphospecies provides strong evidence for geographic transport restriction of a microorganism; i.e., Antarctic protistan communities are less influenced by transport of protists to and from the Antarctic continent than by local adaptation, a subtle form of endemism.

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Rodrigo, Cristian, Jenny M. Blamey, Oliver Huhn e Christine Provost. "Is there an active hydrothermal flux from the Orca seamount in the Bransfield Strait, Antarctica?" Andean Geology 45, n. 3 (6 giugno 2018): 344. http://dx.doi.org/10.5027/andgeov45n3-3086.

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The rifting zone of Bransfield Strait, Antarctica, is tectonically and geologically unique. It is a back-arc basin that was opened by extensional forces associated to roll-back subduction after cessation of spreading activity of the Phoenix Ridge, and the transtension of the westward ending of Scotia-Antarctica Plate boundary. The Bransfield Rift/Ridge is still active generating volcanism or magma rise to force hydrothermal activity. During the ANT-XXV/4 cruise onboard R/V “Polarstern”, standard CTD and beam transmission measurements were done to determine temperature anomaly and turbidity. Water sampling was performed to determine δ3He and to find thermophilic microorganisms to examine the Orca seamount hydrothermal activity. A temperature anomaly of ~0.08 °C, a pick of turbidity, and high value of δ3He (>10%) were found inside Orca seamount. Results are consistent with a hydrothermal flux coming from the seamount. The report of the first observation of thermophilic and hyperthermophilic microorganisms in cold deep Antarctic waters is part of this study. Inside Orca seamount these microorganisms were found at three different depth levels close to the bottom. We suggest that the fluid migration from the volcano resulted from recent magmatic activity and provided the required elemental nutrients for microbial growth. Besides some thermophiles were found outside the seamount in a small quantity close to the seafloor. These would probably be related to subsidiary structures of the Orca seamount, or were transported by currents from other active volcanic sites as Deception Island. The finding of these thermophilic and hyperthermophilic microorganisms raise questions about the dispersal and their resistance in these extreme environments.

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Pearce, David A., K. A. Hughes, T. Lachlan-Cope, S. A. Harangozo e A. E. Jones. "Biodiversity of air-borne microorganisms at Halley station, Antarctica". Extremophiles 14, n. 2 (21 gennaio 2010): 145–59. http://dx.doi.org/10.1007/s00792-009-0293-8.

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Karl, D. M. "Microorganisms in the Accreted Ice of Lake Vostok, Antarctica". Science 286, n. 5447 (10 dicembre 1999): 2144–47. http://dx.doi.org/10.1126/science.286.5447.2144.

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Loperena, Lyliam, Verónica Soria, Hermosinda Varela, Sandra Lupo, Alejandro Bergalli, Mairan Guigou, Andrés Pellegrino et al. "Extracellular enzymes produced by microorganisms isolated from maritime Antarctica". World Journal of Microbiology and Biotechnology 28, n. 5 (14 marzo 2012): 2249–56. http://dx.doi.org/10.1007/s11274-012-1032-3.

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Zucconi, Laura, Fabiana Canini, Marta Elisabetta Temporiti e Solveig Tosi. "Extracellular Enzymes and Bioactive Compounds from Antarctic Terrestrial Fungi for Bioprospecting". International Journal of Environmental Research and Public Health 17, n. 18 (4 settembre 2020): 6459. http://dx.doi.org/10.3390/ijerph17186459.

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Antarctica, one of the harshest environments in the world, has been successfully colonized by extremophilic, psychrophilic, and psychrotolerant microorganisms, facing a range of extreme conditions. Fungi are the most diverse taxon in the Antarctic ecosystems, including soils. Genetic adaptation to this environment results in the synthesis of a range of metabolites, with different functional roles in relation to the biotic and abiotic environmental factors, some of which with new biological properties of potential biotechnological interest. An overview on the production of cold-adapted enzymes and other bioactive secondary metabolites from filamentous fungi and yeasts isolated from Antarctic soils is here provided and considerations on their ecological significance are reported. A great number of researches have been carried out to date, based on cultural approaches. More recently, metagenomics approaches are expected to increase our knowledge on metabolic potential of these organisms, leading to the characterization of unculturable taxa. The search on fungi in Antarctica deserves to be improved, since it may represent a useful strategy for finding new metabolic pathways and, consequently, new bioactive compounds.

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Lo Giudice, Angelina, e Concetta Gugliandolo. "A Special Issue on Microorganisms from Extreme Environments in Memory of Luigi Michaud (1974–2014)". Diversity 12, n. 1 (18 dicembre 2019): 2. http://dx.doi.org/10.3390/d12010002.

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A special issue (SI) titled “Microbial Diversity in Extreme Environments: Implications for Ecological and Applicative Perspectives” has been launched with the aim of showcasing the diversity and biotechnological potential of extremophilic microorganisms. The issue includes 10 research papers and four reviews that mainly address prokaryotes inhabiting hyperarid, hypercold, hyperalkaline and hypersaline (or polyextreme) environments, spanning from deserts to meromictic and glacier lakes around the globe. Thermophilic prokaryotes from shallow hydrothermal vents and Antarctic geothermal soils are also treated. The ecology and biotechnological perspectives of eukaryotes are discussed in two review papers and one research paper. This special issue serves as a memorial to Dr. Luigi Michaud (1974–2014), who dramatically passed away in Antarctica during underwater sampling activities.

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Zakaria, Nur Nadhirah, Claudio Gomez-Fuentes, Khalilah Abdul Khalil, Peter Convey, Ahmad Fareez Ahmad Roslee, Azham Zulkharnain, Suriana Sabri, Noor Azmi Shaharuddin, Leyla Cárdenas e Siti Aqlima Ahmad. "Statistical Optimisation of Diesel Biodegradation at Low Temperatures by an Antarctic Marine Bacterial Consortium Isolated from Non-Contaminated Seawater". Microorganisms 9, n. 6 (3 giugno 2021): 1213. http://dx.doi.org/10.3390/microorganisms9061213.

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Hydrocarbon pollution is widespread around the globe and, even in the remoteness of Antarctica, the impacts of hydrocarbons from anthropogenic sources are still apparent. Antarctica’s chronically cold temperatures and other extreme environmental conditions reduce the rates of biological processes, including the biodegradation of pollutants. However, the native Antarctic microbial diversity provides a reservoir of cold-adapted microorganisms, some of which have the potential for biodegradation. This study evaluated the diesel hydrocarbon-degrading ability of a psychrotolerant marine bacterial consortium obtained from the coast of the north-west Antarctic Peninsula. The consortium’s growth conditions were optimised using one-factor-at-a-time (OFAT) and statistical response surface methodology (RSM), which identified optimal growth conditions of pH 8.0, 10 °C, 25 ppt NaCl and 1.5 g/L NH4NO3. The predicted model was highly significant and confirmed that the parameters’ salinity, temperature, nitrogen concentration and initial diesel concentration significantly influenced diesel biodegradation. Using the optimised values generated by RSM, a mass reduction of 12.23 mg/mL from the initial 30.518 mg/mL (4% (w/v)) concentration of diesel was achieved within a 6 d incubation period. This study provides further evidence for the presence of native hydrocarbon-degrading bacteria in non-contaminated Antarctic seawater.

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Chaya, Aoi, Norio Kurosawa, Akinori Kawamata, Makiko Kosugi e Satoshi Imura. "Community Structures of Bacteria, Archaea, and Eukaryotic Microbes in the Freshwater Glacier Lake Yukidori-Ike in Langhovde, East Antarctica". Diversity 11, n. 7 (6 luglio 2019): 105. http://dx.doi.org/10.3390/d11070105.

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Since most studies about community structures of microorganisms in Antarctic terrestrial lakes using molecular biological tools are mainly focused on bacteria, limited information is available about archaeal and eukaryotic microbial diversity. In this study, the biodiversity of microorganisms belonging to all three domains in a typical Antarctic freshwater glacier lake (Yukidori-Ike) was revealed using small subunit ribosomal RNA (SSU rRNA) clone library analysis. The bacterial clones were grouped into 102 operational taxonomic units (OTUs) and showed significant biodiversity. Betaproteobacteria were most frequently detected, followed by Cyanobacteria, Bacteroidetes, and Firmicutes as major lineages. In contrast to the bacterial diversity, much lower archaeal diversity, consisting of only two OTUs of methanogens, was observed. In the eukaryotic microbial community consisting of 20 OTUs, Tardigradal DNA was remarkably frequently detected. Genera affiliated with the phyla Ciliophora, Cryptomycota, Chlorophyta, Bacillariophyta, and Apusozoa were also detected. The biodiversity and species compositions of the whole microbial community of Lake Yukidori-Ike are similar to those of freshwater environments in temperate regions but are different from saline lakes in Antarctica, indicating that the salinity seems to affect the microbial composition more than the temperature.

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Uetake, Jun, Thomas C. J. Hill, Kathryn A. Moore, Paul J. DeMott, Alain Protat e Sonia M. Kreidenweis. "Airborne bacteria confirm the pristine nature of the Southern Ocean boundary layer". Proceedings of the National Academy of Sciences 117, n. 24 (1 giugno 2020): 13275–82. http://dx.doi.org/10.1073/pnas.2000134117.

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Microorganisms are ubiquitous and highly diverse in the atmosphere. Despite the potential impacts of airborne bacteria found in the lower atmosphere over the Southern Ocean (SO) on the ecology of Antarctica and on marine cloud phase, no previous region-wide assessment of bioaerosols over the SO has been reported. We conducted bacterial profiling of boundary layer shipboard aerosol samples obtained during an Austral summer research voyage, spanning 42.8 to 66.5°S. Contrary to findings over global subtropical regions and the Northern Hemisphere, where transport of microorganisms from continents often controls airborne communities, the great majority of the bacteria detected in our samples were marine, based on taxonomy, back trajectories, and source tracking analysis. Further, the beta diversity of airborne bacterial communities varied with latitude and temperature, but not with other meteorological variables. Limited meridional airborne transport restricts southward community dispersal, isolating Antarctica and inhibiting microorganism and nutrient deposition from lower latitudes to these same regions. A consequence and implication for this region’s marine boundary layer and the clouds that overtop it is that it is truly pristine, free from continental and anthropogenic influences, with the ocean as the dominant source controlling low-level concentrations of cloud condensation nuclei and ice nucleating particles.

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Prather, Hannah M., Angélica Casanova-Katny, Andrew F. Clements, Matthew W. Chmielewski, Mehmet A. Balkan, Erin E. Shortlidge, Todd N. Rosenstiel e Sarah M. Eppley. "Species-specific effects of passive warming in an Antarctic moss system". Royal Society Open Science 6, n. 11 (novembre 2019): 190744. http://dx.doi.org/10.1098/rsos.190744.

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Polar systems are experiencing rapid climate change and the high sensitivity of these Arctic and Antarctic ecosystems make them especially vulnerable to accelerated ecological transformation. In Antarctica, warming results in a mosaic of ice-free terrestrial habitats dominated by a diverse assemblage of cryptogamic plants (i.e. mosses and lichens). Although these plants provide key habitat for a wide array of microorganisms and invertebrates, we have little understanding of the interaction between trophic levels in this terrestrial ecosystem and whether there are functional effects of plant species on higher trophic levels that may alter with warming. Here, we used open top chambers on Fildes Peninsula, King George Island, Antarctica, to examine the effects of passive warming and moss species on the abiotic environment and ultimately on higher trophic levels. For the dominant mosses, Polytrichastrum alpinum and Sanionia georgicouncinata , we found species-specific effects on the abiotic environment, including moss canopy temperature and soil moisture. In addition, we found distinct shifts in sexual expression in P . alpinum plants under warming compared to mosses without warming, and invertebrate communities in this moss species were strongly correlated with plant reproduction. Mosses under warming had substantially larger total invertebrate communities, and some invertebrate taxa were influenced differentially by moss species. However, warmed moss plants showed lower fungal biomass than control moss plants, and fungal biomass differed between moss species. Our results indicate that continued warming may impact the reproductive output of Antarctic moss species, potentially altering terrestrial ecosystems dynamics from the bottom up. Understanding these effects requires clarifying the foundational, mechanistic role that individual plant species play in mediating complex interactions in Antarctica's terrestrial food webs.

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Hughes, Kevin A., Marta Misiak, Yogabaanu Ulaganathan e Kevin K. Newsham. "Importation of psychrotolerant fungi to Antarctica associated with wooden cargo packaging". Antarctic Science 30, n. 5 (ottobre 2018): 298–305. http://dx.doi.org/10.1017/s0954102018000329.

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AbstractThe harsh climatic conditions and low levels of human activity in Antarctica, relative to other regions, means few non-native species have established. However, the risk of introductions is becoming greater as human activity increases. Non-native microorganisms can be imported to Antarctica in association with fresh food, cargo and personal clothing, but the likelihood of their establishment is not well understood. In January 2015, a wooden packing crate, heavily contaminated with fungi, was imported by aircraft from Punta Arenas, Chile, to Rothera Research Station, Antarctica.Mucor racemosusBull. and two strains ofTrichoderma viridescens(A.S. Horne & H.S. Will.) Jaklitsch & Samuels were isolated from the wood. Measurements of hyphal extension rates indicated that all three strains were psychrotolerant and capable of growth at 4°C, withM. racemosusgrowing at 0°C. The imported fungi could grow at rates equivalent to, or faster than, species isolated from Antarctic soils, suggesting that low temperature may not be a limiting factor for establishment. It is recommended that wood heat-treatment standards, equivalent to those described in the International Standards for Phytosanitary Measures No. 15, are employed by national operators importing cargo into Antarctica, and that treated wood is adequately stored to prevent fungal contamination prior to transportation.

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Bratchkova, Anna, e Veneta Ivanova. "Bioactive Metabolites Produced by Microorganisms Collected in Antarctica and the Arctic". Biotechnology & Biotechnological Equipment 25, sup1 (gennaio 2011): 1–7. http://dx.doi.org/10.5504/bbeq.2011.0116.

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Friedmann, E. I., R. O. Friedmann e R. Weed. "Trace fossils of endolithic microorganisms in Antarctica: A model for mars". Origins of Life and Evolution of the Biosphere 16, n. 3-4 (settembre 1986): 350. http://dx.doi.org/10.1007/bf02422067.

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Coufalík, Pavel, Peter Váczi, Ondřej Zvěřina, Kateřina Trnková, Kateřina Skácelová, Miloš Barták e Josef Komárek. "Nitrate and ammonium ions contents in field minibioreactors with Antarctic freshwater autotrophs". Czech Polar Reports 3, n. 2 (1 giugno 2013): 196–207. http://dx.doi.org/10.5817/cpr2013-2-20.

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The content of nitrate and ammonium ions in aquatic environment is an important factor in the development of microorganisms colonies especially in low-nutrient environment. In this study, field experiments using small-volume minibioreactors were performed directly on the James Ross Island in Antarctica in order to describe changes in nitrate and ammonium ions contents in the Antarctic environment The ion concentrations in minibioreactors with local freshwater autotrophs was monitored for increased eutro-phication conditions. The content of nitrogen forms was determined in water samples taken from the minibioreactors regularly. Samples were taken to the laboratory of the Johann Gregor Mendel station where nitrogen content was evaluated using ion-selective electrodes. Furthermore, the freshwater autotrophs was subjected to basic taxonomic study. Closed system of the minibioreactors allowed the monitoring of nitrogen speciation changes which take place in the environment. These changes can be attributed to both the biological activity of microorganisms and external conditions. Increased eutrophication of water did not induce a rapid development of the freshwater autotrophs.

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Okere, Uchechukwu V., Ana Cabrerizo, Jordi Dachs, Kevin C. Jones e Kirk T. Semple. "Biodegradation of phenanthrene by indigenous microorganisms in soils from Livingstone Island, Antarctica". FEMS Microbiology Letters 329, n. 1 (23 febbraio 2012): 69–77. http://dx.doi.org/10.1111/j.1574-6968.2012.02501.x.

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26

Wierzchos, Jacek, e Carmen Ascaso. "Life, decay and fossilisation of endolithic microorganisms from the Ross Desert, Antarctica". Polar Biology 24, n. 11 (1 novembre 2001): 863–68. http://dx.doi.org/10.1007/s003000100296.

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27

Griffin, Benjamin M., e James M. Tiedje. "Microbial reductive dehalogenation in Antarctic melt pond sediments". Antarctic Science 19, n. 4 (2 agosto 2007): 411–16. http://dx.doi.org/10.1017/s0954102007000570.

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Abstract (sommario):

AbstractDue to its geographic isolation and relatively limited human impact, Antarctica is a promising location to study the eco-physiology of natural halogen cycles. Anaerobic sediments from Antarctic melt ponds on Ross Island and on the McMurdo Ice Shelf near Bratina Island were tested for activity of microbial reductive dehalogenation. Anaerobic enrichment cultures were established with potential electron donors and tetrachloroethene, trichloroethene, 2-bromophenol, 2-chlorophenol, 3-bromobenzoate, or 3-chlorobenozoate, as model halocarbon electron acceptors. Dechlorination of aromatic compounds was limited, whereas 2-bromophenol was debrominated in seven of the eight sediments and one site also showed debromination of 3-bromobenzoate. A most probable number estimate with 2-bromophenol at one site revealed 103–104cultivatable debrominators per gram of sediment (wet weight). Chloroethene dechlorination was slow and primarily produced trichloroethene from tetrachloroethene, although bothcis-andtrans-dichloroethene were detected in certain enrichments upon extended incubation. These results demonstrate the presence of reductive dehalogenating activity in anaerobic, Antarctic melt-pond sediments and expand the known metabolic diversity of Antarctic microorganisms.

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28

Smith, Glen A., Peter D. Nichols e David C. White. "Triacylglycerol fatty acid and sterol composition of sediment microorganisms from McMurdo Sound, Antarctica". Polar Biology 9, n. 5 (aprile 1989): 273–79. http://dx.doi.org/10.1007/bf00287423.

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29

Coufalík, Pavel, Petra Prochazková, Ondřej Zvěřina, Kateřina Trnková, Kateřina Skácelová, Daniel Nývlt e Josef Komárek. "Freshwater mineral nitrogen and essential elements in autotrophs in James Ross Island, West Antarctica". Polish Polar Research 37, n. 4 (1 dicembre 2016): 477–91. http://dx.doi.org/10.1515/popore-2016-0025.

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AbstractThe lakes and watercourses are habitats for various communities of cyanobacteria and algae, which are among the few primary producers in Antarctica. The amount of nutrients in the mineral-poor Antarctic environment is a limiting factor for the growth of freshwater autotrophs in most cases. In this study, the main aim was to assess the availability of mineral nitrogen for microorganisms in cyanobacterial mats in James Ross Island. The nitrate and ammonium ions in water environment were determined as well as the contents of major elements (C, N, P, S, Na, K, Ca, Mg, Al, Fe, Mn) in cyanobacterial mats. The molar ratios of C:N, C:P and N:P in mats were in focus. The growth of freshwater autotrophs seems not to be limited by the level of nitrogen, according to the content of available mineral nitrogen in water and the biogeochemical stoichiometry of C:N:P. The source of nutrients in the Ulu Peninsula is not obvious. The nitrogen fixation could enhance the nitrogen content in mats, which was observed in some samples containing theNostocsp.

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30

Rego, Adriana, António G. G. Sousa, João P. Santos, Francisco Pascoal, João Canário, Pedro N. Leão e Catarina Magalhães. "Diversity of Bacterial Biosynthetic Genes in Maritime Antarctica". Microorganisms 8, n. 2 (18 febbraio 2020): 279. http://dx.doi.org/10.3390/microorganisms8020279.

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Abstract (sommario):

Bacterial natural products (NPs) are still a major source of new drug leads. Polyketides (PKs) and non-ribosomal peptides (NRP) are two pharmaceutically important families of NPs and recent studies have revealed Antarctica to harbor endemic polyketide synthase (PKS) and non-ribosomal peptide synthetase (NRPS) genes, likely to be involved in the production of novel metabolites. Despite this, the diversity of secondary metabolites genes in Antarctica is still poorly explored. In this study, a computational bioprospection approach was employed to study the diversity and identity of PKS and NRPS genes to one of the most biodiverse areas in maritime Antarctica—Maxwell Bay. Amplicon sequencing of soil samples targeting ketosynthase (KS) and adenylation (AD) domains of PKS and NRPS genes, respectively, revealed abundant and unexplored chemical diversity in this peninsula. About 20% of AD domain sequences were only distantly related to characterized biosynthetic genes. Several PKS and NRPS genes were found to be closely associated to recently described metabolites including those from uncultured and candidate phyla. The combination of new approaches in computational biology and new culture-dependent and -independent strategies is thus critical for the recovery of the potential novel chemistry encoded in Antarctica microorganisms.

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31

Vincent, Warwick F. "Evolutionary origins of Antarctic microbiota: invasion, selection and endemism". Antarctic Science 12, n. 3 (settembre 2000): 374–85. http://dx.doi.org/10.1017/s0954102000000420.

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Abstract (sommario):

Increasing interest in the ecological roles, conservation and biotechnological potential of Antarctic microbiota has focused attention on their biodiversity and evolutionary origins. Antarctic microbial ecosystems provide useful models for general questions in evolutionary ecology given the relative isolation of the South Polar Region, the severe biological constraints imposed by the polar environment, and the absence of higher plants and animals in some Antarctic habitats. Sealed environments such as Lake Vostok and the overlying East Antarctic ice sheet provide unique, natural culture collections for studying microorganisms that have been isolated from the global gene pool over timescales of evolutionary significance. Most Antarctic environments, however, continue to receive microbial propagules from outside the region, as indicated by spore trap data, the microflora found in Antarctic snow and ice, the colonising taxa at geothermal sites, and the high frequency of apparently cosmopolitan species in most habitats. Differences in environmental stability and selection pressure among environments are likely to influence the degree of adaptive radiation and microbial endemism. The latter seems greater in the Southern Ocean by comparison with non-marine ecosystems of Antarctica, although there is some evidence of endemic species in highly specialised niches on the continent such as in the endolithic habitat and saline lakes. Analytical techniques such as 16S rDNA sequencing and DNA–DNA hybridisation are beginning to provide new insights into the genetic affinities and biodiversity of Antarctic microbiota, and are leading to a more rigorous evaluation of microbial endemism.

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32

Vasileva-Tonkova, Evgenia, e Victoria Gesheva. "Potential for Biodegradation of Hydrocarbons by Microorganisms Isolated from Antarctic Soils". Zeitschrift für Naturforschung C 59, n. 1-2 (1 febbraio 2004): 140–45. http://dx.doi.org/10.1515/znc-2004-1-227.

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Seventeen pure aerobic microbial isolates were obtained from soil samples of three regions of Antarctica: Casey Station, Dewart Island and Terra Nova Bay. Most of them were gram positive coryneform bacteria. Isolates were tested for their ability to grow on mineral salt agar plates supplemented with one of the following model n-alkanes or aromatic hydrocarbons: hexane, heptane, paraffin, benzene, toluene, naphthalene and kerosene. Cell hydrophobicity, the ability to produce anionic glycolipids and extracellular emulsifying activity were also determined and assessed on the basis of growth of soil isolates on hydrocarbons. This study revealed degraders with broader abilities to grow on both types of hydrocarbons, good production of glycolipids and emulsifying activity. On this basis, a mixed culture of strains is proposed, which may find application for bioremediation at temperate temperature of soil environments polluted with different hydrocarbons.

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33

Cavanagh, J. E., P. D. Nichols, P. D. Franzmann e T. A. Mcmeekin. "Hydrocarbon degradation by Antarctic coastal bacteria". Antarctic Science 10, n. 4 (dicembre 1998): 386–97. http://dx.doi.org/10.1017/s0954102098000479.

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Abstract (sommario):

Bacterial cultures obtained through selective enrichment of beach sand collected 60 days and one year after treatment of sites in a pilot oil spill trial conducted at Airport Beach, Vestfold Hills, East Antarctica, were examined for the ability to degrade n-alkanes and phenanthrene. The effects of different hydrocarbon mixtures (Special Antarctic Blend [SAB] and BP-Visco), fish oil [orange roughy]) and inoculation of replicate sites with water from Organic Lake (previously shown to contain hydrocarbon-degrading bacteria) on the indigenous microbial population were examined. Of the cultures obtained, those from sites treated with SAB and BP-Visco degraded n-alkanes most consistently and typically to the greatest extent. Two mixed cultures obtained from samples collected at 60 days and two isolates obtained from these cultures extensively degraded phenanthrene. 1-Hydroxy-naphthoic acid formed the major phenanthrene metabolite. Lower levels of salicylic acid, 1-naphthol, 1, 4-naphthaquinone and phenanthrene 9-10 dihydrodiol were detected in extracts of phenanthrene grown cultures. This study shows that under laboratory conditions indigenous Antarctic bacteria can degrade n-alkanes and the more recalcitrant polycyclic aromatic hydrocarbon, phenanthrene. The enrichment of hydrocarbon degrading microorganisms in Antarctic ecosystems exposed to hydrocarbons is relevant for the long term fate hydrocarbon spills in this environment.

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34

Gran-Scheuch, Alejandro, Javiera Ramos-Zuñiga, Edwar Fuentes, Denisse Bravo e José M. Pérez-Donoso. "Effect of Co-contamination by PAHs and Heavy Metals on Bacterial Communities of Diesel Contaminated Soils of South Shetland Islands, Antarctica". Microorganisms 8, n. 11 (7 novembre 2020): 1749. http://dx.doi.org/10.3390/microorganisms8111749.

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Diesel oil is the main source of energy used in Antarctica. Since diesel is composed of toxic compounds such as polycyclic aromatic hydrocarbons (PAHs) and heavy metals, it represents a constant threat to the organisms inhabiting this continent. In the present study, we characterized the chemical and biological parameters of diesel-exposed soils obtained from King George Island in Antarctica. Contaminated soils present PAH concentrations 1000 times higher than non-exposed soils. Some contaminated soil samples also exhibited high concentrations of cadmium and lead. A 16S metagenome analysis revealed the effect of co-contamination on bacterial communities. An increase in the relative abundance of bacteria known as PAH degraders or metal resistant was determined in co-contaminated soils. Accordingly, the soil containing higher amounts of PAHs exhibited increased dehydrogenase activity than control soils, suggesting that the microorganisms present can metabolize diesel. The inhibitory effect on soil metabolism produced by cadmium was lower in diesel-contaminated soils. Moreover, diesel-contaminated soils contain higher amounts of cultivable heterotrophic, cadmium-tolerant, and PAH-degrading bacteria than control soils. Obtained results indicate that diesel contamination at King George island has affected microbial communities, favoring the presence of microorganisms capable of utilizing PAHs as a carbon source, even in the presence of heavy metals.

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35

Emnet, Philipp, Rai S. Kookana, Ali Shareef, Sally Gaw, Mike Williams, Deborah Crittenden e Grant L. Northcott. "The effect of irradiance and temperature on the role of photolysis in the removal of organic micropollutants under Antarctic conditions". Environmental Chemistry 10, n. 5 (2013): 417. http://dx.doi.org/10.1071/en12089.

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Abstract (sommario):

Environmental context Antarctica has several scientific research stations located along its coast, where they discharge often untreated sewage containing organic micropollutants. Although degradation of these pollutants by microorganisms is limited by the cold conditions, other pathways such as photodegradation may be significant. Our results indicate that, during the summer, photolysis is a potentially significant degradation pathway for organic micropollutants in Antarctic surface waters, although the rate of loss would depend on ice cover and water depth. Abstract Knowledge of the environmental fate of organic micropollutants in Antarctica is limited, especially with respect to photolysis. The Antarctic is characterised by extreme light conditions of either continuous sunshine or darkness depending on the season. The photolytic degradation of benzophenone-3 (BP-3), bisphenol A (BPA), 17α-ethinylestradiol (EE2), methyl paraben (mParaben), 4-t-octylphenol (4-t-OP) and triclosan in MilliQ and seawater was investigated over a range of irradiance levels and temperatures. Photodegradation was compound specific. Up to 20% of BPA, BP-3 and EE2 was degraded over a 7-h irradiance period. Triclosan and 4-t-OP degraded to below the limit of detection in all experiments whereas mParaben was not degraded. The degradation of triclosan increased with irradiance in both MilliQ (P=2.2×10–16) and seawater (P=2.2×10–16). The degradation of 4-t-OP increased with irradiance in MilliQ (P=8.5×10–9) and seawater (P=1.1×10–5), and with temperature in MilliQ (P=8.5×10–9) and seawater (P=1.0×10–5). Similar relationships could not be established for BPA, BP-3, EE2 and mParaben due to the limited extent of degradation observed. The photolysis of triclosan was enhanced 4-fold in seawater compared to MilliQ water. Results from this study indicate that micropollutants may persist for extended periods of time in Antarctic coastal waters, particularly with ice cover, above and beyond that exhibited in temperate seawater.

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36

Lee, Gillian Li Yin, Nur Nadhirah Zakaria, Peter Convey, Hiroyuki Futamata, Azham Zulkharnain, Kenshi Suzuki, Khalilah Abdul Khalil et al. "Statistical Optimisation of Phenol Degradation and Pathway Identification through Whole Genome Sequencing of the Cold-Adapted Antarctic Bacterium, Rhodococcus sp. Strain AQ5-07". International Journal of Molecular Sciences 21, n. 24 (9 dicembre 2020): 9363. http://dx.doi.org/10.3390/ijms21249363.

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Abstract (sommario):

Study of the potential of Antarctic microorganisms for use in bioremediation is of increasing interest due to their adaptations to harsh environmental conditions and their metabolic potential in removing a wide variety of organic pollutants at low temperature. In this study, the psychrotolerant bacterium Rhodococcus sp. strain AQ5-07, originally isolated from soil from King George Island (South Shetland Islands, maritime Antarctic), was found to be capable of utilizing phenol as sole carbon and energy source. The bacterium achieved 92.91% degradation of 0.5 g/L phenol under conditions predicted by response surface methodology (RSM) within 84 h at 14.8 °C, pH 7.05, and 0.41 g/L ammonium sulphate. The assembled draft genome sequence (6.75 Mbp) of strain AQ5-07 was obtained through whole genome sequencing (WGS) using the Illumina Hiseq platform. The genome analysis identified a complete gene cluster containing catA, catB, catC, catR, pheR, pheA2, and pheA1. The genome harbours the complete enzyme systems required for phenol and catechol degradation while suggesting phenol degradation occurs via the β-ketoadipate pathway. Enzymatic assay using cell-free crude extract revealed catechol 1,2-dioxygenase activity while no catechol 2,3-dioxygenase activity was detected, supporting this suggestion. The genomic sequence data provide information on gene candidates responsible for phenol and catechol degradation by indigenous Antarctic bacteria and contribute to knowledge of microbial aromatic metabolism and genetic biodiversity in Antarctica.

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37

Bölter, Manfred. "Soil development and soil biology on King George Island, Maritime Antarctic". Polish Polar Research 32, n. 2 (1 gennaio 2011): 105–16. http://dx.doi.org/10.2478/v10183-011-0002-z.

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Soil development and soil biology on King George Island, Maritime AntarcticThis review covers aspects of soil science and soil biology of Antarctica with special focus on King George Island, South Shetlands, the martitime Antarctic. New approaches in soil descriptions and soil taxonomy show a great variety of soil types, related to different parent material, mainly volcanic origin, as well as on influences by soil biological processes. The spread of higher rooting plants attract microorganisms, nematodes and collemboles which in turn build new organic material and change the environment for further successors. Microbial communities are drivers with respect to metabolic and physiological properties indicating a great potential in a changing environment. The literature review also shows a lack of investigations on processes of carbon and nitrogen turnover, despite wide knowledge on its standing stock in different environments. Further, only few reports were found on the processes of humification. Only few data are available which can be regarded as long term monitorings, hence, such projects need to be established in order to follow ecological changes.

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38

Darham, Syazani, Khadijah Nabilah Mohd Zahri, Azham Zulkharnain, Suriana Sabri, Claudio Gomez-Fuentes, Peter Convey, Khalilah Abdul Khalil e Siti Aqlima Ahmad. "Statistical Optimisation and Kinetic Studies of Molybdenum Reduction Using a Psychrotolerant Marine Bacteria Isolated from Antarctica". Journal of Marine Science and Engineering 9, n. 6 (11 giugno 2021): 648. http://dx.doi.org/10.3390/jmse9060648.

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Abstract (sommario):

The extensive industrial use of the heavy metal molybdenum (Mo) has led to an emerging global pollution with its traces that can even be found in Antarctica. In response, a reduction process that transforms hexamolybdate (Mo6+) to a less toxic compound, Mo-blue, using microorganisms provides a sustainable remediation approach. The aim of this study was to investigate the reduction of Mo by a psychrotolerant Antarctic marine bacterium, Marinomonas sp. strain AQ5-A9. Mo reduction was optimised using One-Factor-At-a-Time (OFAT) and Response Surface Methodology (RSM). Subsequently, Mo reduction kinetics were further studied. OFAT results showed that maximum Mo reduction occurred in culture media conditions of pH 6.0 and 50 ppt salinity at 15 °C, with initial sucrose, nitrogen and molybdate concentrations of 2.0%, 3.0 g/L and 10 mM, respectively. Further optimization using RSM identified improved optimum conditions of pH 6.0 and 47 ppt salinity at 16 °C, with initial sucrose, nitrogen and molybdate concentrations of 1.8%, 2.25 g/L and 16 mM, respectively. Investigation of the kinetics of Mo reduction revealed Aiba as the best-fitting model. The calculated Aiba coefficient of maximum Mo reduction rate (µmax) was 0.067 h−1. The data obtained support the potential use of marine bacteria in the bioremediation of Mo.

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39

Brovarska, O. S., L. D. Varbanets, G. V. Gladka, A. D. German e O. B. Tashyrev. "Lipopolysaccharide of Pseudomonas mandelii, Isolated from Antarctica". Mikrobiolohichnyi Zhurnal 83, n. 4 (17 agosto 2021): 24–34. http://dx.doi.org/10.15407/microbiolj83.04.024.

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Abstract (sommario):

Representatives of the Pseudomonas mandelii species are able to exist and multiply in places where the temperature is constantly low. The optimum growth temperature for P. mandelii is 25–30°C, although this bacterium can grow at 4°C but not at 37°C. Therefore, P. mandelii is an excellent example of psychrotolerant bacterium which like psychrophilic bacteria is characterized by a number of structural and functional adaptations that facilitate survival at low temperatures. To understand these microorganisms’ role in Antarctica the characterization of its biopolymers is vital. One of these biopolymers is lipopolysaccharide (LPS), composition and structure of which are diagnostically significant. This determines the aim of the work – to isolate lipopolysaccharides from the cells of Antarctic strain of P. mandelii, grown at different temperatures, to characterize them chemically, and to study their functional and biological activity. Methods. The object of the study was Pseudomonas sp. U1, isolated from moss on Galindez Island in Antarctica. Lipopolysaccharides were extracted from dried cells by 45% phenol water solution at 65–68°С by Westphal and Jann method. The amount of carbohydrates was determined by phenol-sulfuric method. Carbohydrate content was determined in accordance to the calibration curve, which was built using glucose as a standard. The content of nucleic acids was determined by Spirin, protein − by Lowry method. Serological activity of LPS was investigated by double immunodiffusion in agar using the method of Ouchterlony. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAAG electrophoresis) was performed according to Laemmli. Results. As a result of phylogenetic analysis (programs ClustalX 2.1, Tree view, Mega v. 6.00) it was shown that the Antarctic bacterial strain Pseudomonas sp. U1 associated with green moss has a 99.4% homology with the type strain from the GenBank database NR024902 P. mandelii CIP 105273T. According to these data and proximity to the corresponding cluster of species, the studied isolate can be identified as P. mandelii. A characteristic feature of LPS isolated from P. mandelii cells, grown at different temperatures (20°C and 4°C) is their heterogeneity. This is evidenced by the data of the monosaccharide composition, electrophoretic distribution, which showed that P. mandelii produces S- and SR-forms of LPS, differed in the length of the O-specific polysaccharide chains. The R-form of LPS is also present, which does not contain an O-specific polysaccharide chains. Structural heterogeneity is also inherent in LPS lipid A. This is evidenced by the data of the fatty acid composition. In LPS grown at 4°C no unsaturated fatty acids were found, while such ones are synthesized in LPS of other bacteria grown in the cold, in response to a decrease in growth temperature. The study of the immunochemical properties of LPS was carried out using polyclonal O-antisera as antibodies, and LPS as antigens indicated that in homologous systems LPS exhibited serological activity. LPS obtained from P. mandelii U1 cells, grown at 20°C, had a complex antigenic composition and gave two clear lines of precipitation at a concentration of 1 mg/mL. LPS obtained from P. mandelii U1 cells, grown at 4°C, gave one line, which indicates their serological homogeneity. Conclusions. For the first time lipopolysaccharides were isolated from cells of P. mandelii U1, grown at 4°C and 20°С. A characteristic feature of these LPS is their heterogeneity. This is evidenced by the data of the monosaccharide and fatty acid composition, electrophoretic distribution, which showed that P. mandelii produces S- and SR-forms of LPS, differed in the length of the O-specific polysaccharide chains. LPS, obtained from cells, grown at different temperatures, are differed by serological activity.

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40

Nixon, Sophie L., Jon P. Telling, Jemma L. Wadham e Charles S. Cockell. "Viable cold-tolerant iron-reducing microorganisms in geographically diverse subglacial environments". Biogeosciences 14, n. 6 (21 marzo 2017): 1445–55. http://dx.doi.org/10.5194/bg-14-1445-2017.

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Abstract (sommario):

Abstract. Subglacial environments are known to harbour metabolically diverse microbial communities. These microbial communities drive chemical weathering of underlying bedrock and influence the geochemistry of glacial meltwater. Despite its importance in weathering reactions, the microbial cycling of iron in subglacial environments, in particular the role of microbial iron reduction, is poorly understood. In this study we address the prevalence of viable iron-reducing microorganisms in subglacial sediments from five geographically isolated glaciers. Iron-reducing enrichment cultures were established with sediment from beneath Engabreen (Norway), Finsterwalderbreen (Svalbard), Leverett and Russell glaciers (Greenland), and Lower Wright Glacier (Antarctica). Rates of iron reduction were higher at 4 °C compared with 15 °C in all but one duplicated second-generation enrichment culture, indicative of cold-tolerant and perhaps cold-adapted iron reducers. Analysis of bacterial 16S rRNA genes indicates Desulfosporosinus were the dominant iron-reducing microorganisms in low-temperature Engabreen, Finsterwalderbreen and Lower Wright Glacier enrichments, and Geobacter dominated in Russell and Leverett enrichments. Results from this study suggest microbial iron reduction is widespread in subglacial environments and may have important implications for global biogeochemical iron cycling and export to marine ecosystems.

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41

Nuñez, Martin A., Romina D. Dimarco, Ian A. Dickie e Aníbal Pauchard. "What can possibly go wrong?: The risks of introducing soil microorganisms from Antarctica into South America". Bosque (Valdivia) 36, n. 3 (2015): 343–46. http://dx.doi.org/10.4067/s0717-92002015000300001.

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42

Bulat, S. A., I. A. Alekhina, V. Ya Lipenkov, V. V. Lukin, D. Marie e J. R. Petit. "Cell concentrations of microorganisms in glacial and lake ice of the Vostok ice core, East Antarctica". Microbiology 78, n. 6 (dicembre 2009): 808–10. http://dx.doi.org/10.1134/s0026261709060216.

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43

Vosjan, J. H., G. Döhler e G. Nieuwland. "Effect of UV-B irradiance on the ATP content of microorganisms of the Weddell Sea (Antarctica)". Netherlands Journal of Sea Research 25, n. 3 (giugno 1990): 391–93. http://dx.doi.org/10.1016/0077-7579(90)90046-j.

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44

T., Bedernichek, e Рartyka Т. "Content of water-soluble carbohydrates as a quality indicator of cryogenic soils". Proceedings of the State Natural History Museum, n. 34 (20 novembre 2019): 43–48. http://dx.doi.org/10.36885/nzdpm.2018.34.43-48.

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Abstract (sommario):

The content of water-soluble organic matter in the soil is an important indicator of its quality and affects physical, chemical and biological properties of soil. This indicator is widely used for assessment of most zonal soils. However, in some cases, accumulation rates of water-soluble organic compounds in soil may significantly exceed the rate of their destruction. If so, it is more important to quantify not only the fraction of water-soluble organic matter as a whole but also to determine its composition. In this context, it is important to determine the content of the most labile and available for microorganisms compound – water-soluble carbohydrates. In this paper, the content of water-soluble carbohydrates and water-soluble organic matter in soils of Coastal Antarctica was estimated. Soils under three different plant communities were studied. We found that water-soluble organic matter of studied soils may contain up to 50% of carbohydrates. Hence, further research is needed to study other soils of Coastal Antarctica to determine their vulnerability to global climate change

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45

Gesheva, Victoria. "Production of antibiotics and enzymes by soil microorganisms from the windmill islands region, Wilkes Land, East Antarctica". Polar Biology 33, n. 10 (28 maggio 2010): 1351–57. http://dx.doi.org/10.1007/s00300-010-0824-x.

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46

Elster, J., R. J. Delmas, J. R. Petit e K. Řeháková. "Composition of microbial communities in aerosol, snow and ice samples from remote glaciated areas (Antarctica, Alps, Andes)". Biogeosciences Discussions 4, n. 3 (19 giugno 2007): 1779–813. http://dx.doi.org/10.5194/bgd-4-1779-2007.

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Abstract (sommario):

Abstract. Taxonomical and ecological analyses were performed on micro-autotrophs (cyanobacteria and algae together with remnants of diatom valves), micro-fungi (hyphae and spores), bacteria (rod, cocci and red clusters), yeast, and plant pollen extracted from various samples: Alps snow (Mt. Blank area), Andean snow (Illimani, Bolivia), Antarctic aerosol filters (Dumont d'Urville, Terre Adélie), and Antarctic inland ice (Terre Adélie). Three methods for ice and snow sample's pre-concentration were tested (filtration, centrifugation and lyophilisation). Afterwards, cultivation methods for terrestrial, freshwater and marine microorganisms (micro-autotrophs and micro-fungi) were used in combination with liquid and solid media. The main goal of the study was to find out if micro-autotrophs are commonly transported by air masses, and later stored in snow and icecaps around the world. The most striking result of this study was the absence of culturable micro-autotrophs in all studied samples. However, an unusual culturable pigmented prokaryote was found in both alpine snow and aerosol samples. Analyses of many samples and proper statistical analyses (PCA, RDA- Monte Carlo permutation tests) showed that studied treatments highly significantly differ in both microbial community and biotic remnants composition F=9.33, p=0.001. In addition, GLM showed that studied treatments highly significantly differ in numbers of categories of microorganisms and remnants of biological material F=11.45, p=0.00005. The Antarctic aerosol samples were characterised by having red clusters of bacteria, the unusual prokaryote and yeasts. The high mountain snow from the Alps and Andes contained much more culturable heterotrophs. The unusual prokaryote was very abundant, as were coccoid bacteria, red clusters of bacteria, as well as yeasts. The Antarctic ice samples were quite different. These samples had higher numbers of rod bacteria and fungal hyphae. The microbial communities and biological remnants of analysed samples comprises two communities, without a sharp boundary between them: i) the first community includes ubiquitous organisms including contaminants, ii) the second community represents individuals frequently occurring in remote terrestrial cold or hot desert/semi-desert and/or marginal soil-snow-ice ecosystems.

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Liu, Kezhen, Haitao Ding, Yong Yu e Bo Chen. "A Cold-Adapted Chitinase-Producing Bacterium from Antarctica and Its Potential in Biocontrol of Plant Pathogenic Fungi". Marine Drugs 17, n. 12 (10 dicembre 2019): 695. http://dx.doi.org/10.3390/md17120695.

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To obtain chitinase-producing microorganisms with high chitinolytic activity at low temperature, samples collected from Fildes Peninsula in Antarctica were used as sources for bioprospecting of chitinolytic microorganisms. A cold-adapted strain, designated as GWSMS-1, was isolated from marine sediment and further characterized as Pseudomonas. To improve the chitinase production, one-factor-at-a-time and orthogonal test approaches were adopted to optimize the medium components and culture conditions. The results showed that the highest chitinolytic activity (6.36 times higher than that before optimization) was obtained with 95.41 U L−1 with 15 g L−1 of glucose, 1 g L−1 of peptone, 15 g L−1 of colloid chitin and 0.25 g L−1 of magnesium ions contained in the medium, cultivated under pH 7.0 and a temperature of 20 °C. To better understand the application potential of this strain, the enzymatic properties and the antifungal activity of the crude chitinase secreted by the strain were further investigated. The crude enzyme showed the maximum catalytic activity at 35 °C and pH 4.5, and it also exhibited excellent low-temperature activity, which still displayed more than 50% of its maximal activity at 0 °C. Furthermore, the crude chitinase showed significant inhibition of fungi Verticillium dahlia CICC 2534 and Fusarium oxysporum f. sp. cucumerinum CICC 2532, which can cause cotton wilt and cucumber blight, respectively, suggesting that strain GWSMS-1 could be a competitive candidate for biological control in agriculture, especially at low temperature.

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48

Abneuf, Mohammed A., Abiramy Krishnan, Marcelo Gonzalez Aravena, Ka-Lai Pang, Peter Convey, Nuradilla Mohamad-Fauzi, Mohammed Rizman-Idid e Siti Aisyah Alias. "Antimicrobial activity of microfungi from maritime Antarctic soil". Czech Polar Reports 6, n. 2 (1 luglio 2016): 141–54. http://dx.doi.org/10.5817/cpr2016-2-13.

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The search for cold-adapted and cold-active fungi in extreme environments provides the potential for discovering new species and novel bioactive compounds. In this study, soil samples were collected from Deception Island, Wilhelmina Bay (north-west Antarctic Peninsula, Graham Land) and Yankee Bay (Greenwich Island), maritime Antarctica, for the isolation of soil fungi and determination of their antimicrobial activity. The soil-plate method, agar block, disc diffusion and broth micro-dilution assays were applied to characterize the thermal classes and antimicrobial activity of the isolated fungi. A total of 27 isolates of fungi were obtained from 14 soil samples, including 13 Ascomycota, 4 Zygomycota and 10 anamorphic fungi. Cold-active (psychrotolerant) fungi predominated over cold-adapted (psychrophilic) fungi. In the antimicrobial assay, 16 isolates showed substantial inhibitory activity against test bacterial pathogens. Ethyl acetate extracts of 10 competent isolates showed significant inhibition of bacterial pathogens. Antifungal activity was observed in the disc diffusion assay, but not in the agar block assay. Minimum inhibitory, bactericidal and fungicidal concentrations were determined using the broth micro-dilution method, with an average in the range of 0.78-25 mg ml-1 on the test microorganisms. Isolate WHB-sp. 7 showed the best broad spectrum antimicrobial activity, with the potential for biotechnological studies in antibiotic development.

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49

Coleine, Claudia, Nuttapon Pombubpa, Laura Zucconi, Silvano Onofri, Benedetta Turchetti, Pietro Buzzini, Jason E. Stajich e Laura Selbmann. "Uncovered Microbial Diversity in Antarctic Cryptoendolithic Communities Sampling Three Representative Locations of the Victoria Land". Microorganisms 8, n. 6 (23 giugno 2020): 942. http://dx.doi.org/10.3390/microorganisms8060942.

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The endolithic niche represents an ultimate refuge to microorganisms in the Mars-like environment of the Antarctic desert. In an era of rapid global change and desertification, the interest in these border ecosystems is increasing due to speculation on how they maintain balance and functionality at the dry limits of life. To assure a reliable estimation of microbial diversity, proper sampling must be planned in order to avoid the necessity of re-sampling as reaching these remote locations is risky and requires tremendous logistical and economical efforts. In this study, we seek to determine the minimum number of samples for uncovering comprehensive bacterial and fungal diversity, comparing communities in strict vicinity to each other. We selected three different locations of the Victoria Land (Continental Antarctica) at different altitudes and showing sandstone outcrops of a diverse nature and origin—Battleship promontory (834 m above sea level (a.s.l.), Southern VL), Trio Nunatak (1,470 m a.s.l., Northern VL) and Mt New Zealand (3,100 m a.s.l., Northern VL). Overall, we found that a wider sampling would be required to capture the whole amplitude of microbial diversity, particularly in Northern VL. We concluded that the inhomogeneity of the rock matrix and the stronger environmental pressure at higher altitudes may force the communities to a higher local diversification.

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50

Siegert, Martin J., John C. Priscu, Irina A. Alekhina, Jemma L. Wadham e W. Berry Lyons. "Antarctic subglacial lake exploration: first results and future plans". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 374, n. 2059 (28 gennaio 2016): 20140466. http://dx.doi.org/10.1098/rsta.2014.0466.

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After more than a decade of planning, three attempts were made in 2012–2013 to access, measure in situ properties and directly sample subglacial Antarctic lake environments. First, Russian scientists drilled into the top of Lake Vostok, allowing lake water to infiltrate, and freeze within, the lower part of the ice-core borehole, from which further coring would recover a frozen sample of surface lake water. Second, UK engineers tried unsuccessfully to deploy a clean-access hot-water drill, to sample the water column and sediments of subglacial Lake Ellsworth. Third, a US mission successfully drilled cleanly into subglacial Lake Whillans, a shallow hydraulically active lake at the coastal margin of West Antarctica, obtaining samples that would later be used to prove the existence of microbial life and active biogeochemical cycling beneath the ice sheet. This article summarizes the results of these programmes in terms of the scientific results obtained, the operational knowledge gained and the engineering challenges revealed, to collate what is known about Antarctic subglacial environments and how to explore them in future. While results from Lake Whillans testify to subglacial lakes as being viable biological habitats, the engineering challenges to explore deeper more isolated lakes where unique microorganisms and climate records may be found, as exemplified in the Lake Ellsworth and Vostok missions, are considerable. Through international cooperation, and by using equipment and knowledge of the existing subglacial lake exploration programmes, it is possible that such environments could be explored thoroughly, and at numerous sites, in the near future.

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