Bibliografie tematiche / Microorganisms – Antarctica

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Letteratura scientifica selezionata sul tema "Microorganisms – Antarctica"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 18 febbraio 2022

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Articoli di riviste sul tema "Microorganisms – Antarctica"

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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Più fonti

Tesi sul tema "Microorganisms – Antarctica"

Dieser, Markus. "Ecosystem dynamics and temporal variations in a microbially dominated, coastal antarctic lake". Thesis, Montana State University, 2009. http://etd.lib.montana.edu/etd/2009/dieser/DieserM1209.pdf.

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This study investigated the microbial ecology of Pony Lake, Antarctica. The main objectives of this research were to 1) characterize physicochemical parameters in Pony Lake during the transition from ice covered to ice free, 2) highlight seasonal and inter-seasonal alterations in lake parameters, 3) relate the physicochemical conditions in the ice and water column to microbial processes and community structure, 4) characterize the effects of phototransformation of dissolved organic matter (DOM) on its bioavailability to bacteria, and 5) demonstrate the role of carotenoid pigments in protecting cells against environmental stresses. Also included are results from three McMurdo Dry Valley lakes on the survivability of microbes encapsulated within the lake ice covers. The results of this study highlight the sensitivity of Antarctic environments and the close coupling of environmental conditions and biological processes. Inter-seasonal differences in weather conditions and snow accumulation strongly affected the physicochemistry of this lacustrine system. Biological processes were closely tied to the physicochemical lake conditions. As a consequence planktonic abundances, production rates, and community structure evolved distinctly in each year. Bacterial production was regulated by the quality of DOM. Whereas nutrient availability appeared to play a minor role in eutrophic Pony Lake water, it became more critical for microbial communities found within the ice column of Antarctic lakes. Especially in the ice cover of the McMurdo Dry Valley lakes, enhanced microbial diversity and survivability was associated with particles (nutrient enriched micro-zones) within an otherwise ultra-oligotrophic habitat. In Pony Lake ice, microbial activity and community structure differed with respect to different strata within the ice column, induced by freeze-concentration of solutes, bioavailability of DOM, and oxygen gradients. A comparison of carotenoid pigmented and non-pigmented heterotrophic bacteria indicated that pigmentation provides enhanced resistance to environmental stresses such as freeze-thaw cycles or solar radiation. Collectively, the Pony Lake data demonstrated that microorganisms that persist throughout the year were able to survive much more severe conditions while entrapped within the ice compared to those observed in the lake water during summer months. Further, this study contributes to a better understanding of the biogeochemical carbon cycle in a microbially dominated system.

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Witowski, Chris G. "Investigation of Bioactive Metabolites from the Antarctic Sponge Dendrilla membranosa and Marine Microorganisms". Scholar Commons, 2015. https://scholarcommons.usf.edu/etd/5602.

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Natural products continue to be a valuable source of compounds in research involving chemical ecology and drug discovery. Secondary metabolites are biosynthesized to benefit the host organism in its environment (feeding deterrence from predators, antibiotic properties to avoid infection, etc.) but these compounds also serve as useful scaffolds in drug discovery applications. The research herein describes both aspects of these two branches of natural products chemistry. The Antarctic sponge Dendrilla membranosa produces diterpenes, of which membranolide A, deters feeding of the predatory amphipod Gondogenia antarctica. A metabolomic study of several sponges was undertaken to determine environmental factors that govern the metabolism of D. membranosa. Habitat specificity, above or below the algal canopy, was a significant factor for the chemical clustering of sponges as well as the abundance of potential amphipod predators that are prevalent within the canopy. Another D. membranosa diterpene, aplysulphurin, undergoes degradation upon methanolic treatment to form the methoxy membranolides B-H. An investigation of these artifacts reveals potent activity against the leishmaniasis-causing parasite Leishmania donovani. Microorganisms also generate a significant number of bioactive natural products. Biotic and abiotic culture stressors such as co-culturing and epigenetic modification, respectively, will be explored to turn on cryptic biosynthetic pathways. These techniques are shown to produce unique secondary metabolites from cultures and further reinforce the one strain many compounds approach to the versatile and formidable microbial domain.

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Moore, Joel Grant. "Diversity, productivity, and physiology of microorganisms in the stream-moat-lake transition of Lake Bonney, Antarctica". Thesis, Montana State University, 2007. http://etd.lib.montana.edu/etd/2007/moore/MooreJ0507.pdf.

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Patel, Angira N. "IDENTIFICATION AND COMPARISION OF FUNGI FROM DIFFERENT DEPTHS OF ANCIENT GLACIAL ICE". Bowling Green State University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1141752883.

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Spackeen, Jenna Lee. "Impact of Climate Change Variables on Nutrient Cycling by Marine Microorganisms in the Southern California Bight and Ross Sea, Antarctica". W&M ScholarWorks, 2017. https://scholarworks.wm.edu/etd/1516639564.

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Ocean environments are being impacted by climate warming, elevated carbon dioxide (CO2) levels, and shifting nutrient sources and sinks. It is essential to quantify the sensitivity of microorganisms to these effects of global change because they form the base of the marine food web and are an integral component of nutrient cycling on the planet. their role in photosynthesis, nutrient uptake, and transfer of organic matter into higher trophic levels or to the deep ocean via the biological pump render microorganisms key in ecosystem structure and function and in regulating the global climate. The goal of this dissertation research was to determine how changing environmental conditions impact microbial communities and the rates at which they take up nutrients. Research for this dissertation took place in the Southern California Bight and in the Ross Sea, Antarctica, where fully factorial designs were used to investigate the response of microorganisms to multiple global change parameters. Nutrient uptake rates were measured using 13C and 15N stable isotopes for carbon and nitrogen substrates and 33P radioisotopes for phosphorus substrates. In the Southern California Bight, a microbial assemblage was collected and incubated in an ‘ecostat’ continuous culture system, where elevated temperature, CO2, and the dominant nitrogen substrate (nitrate or urea) in the diluent were manipulated. During this experiment uptake rates of dissolved inorganic carbon (DIC), nitrate (NO3-), and urea were determined for two microbial size classes (0.7-5.0 μm and >5.0 μm). Urea uptake rates were greater than NO3-, and uptake rates of urea and DIC for both size fractions increased at elevated temperature, while uptake rates of NO3- by smaller microorganisms increased when CO2 levels were high. In the Ross Sea, the impact of elevated temperature, CO2, and iron addition on DIC and NO3- uptake rates by two size classes (0.7-5.0 μm and >5.0 μm) of a late-season microbial community were investigated using a semi-continuous and continuous ‘ecostat’ culturing approach. Temperature impacted the microbial community the most, significantly increasing NO3- and DIC uptake rates by larger microorganisms. The effects of iron addition were more apparent when temperature was also elevated, and CO2 did not impact rates. Bioassay experiments were also conducted in the Ross Sea to determine how increasing and decreasing the N:P supply ratio in combination with other parameters (temperature and iron) impact uptake rates of DIC, NO3-, and amino acids. Results from these experiments show that changes to the dissolved N:P supply ratio have the potential to alter nutrient uptake rates over short time scales, but that temperature elevation and iron addition have a larger impact. Additional experiments were completed on diatoms (Fragilariopsis cylindrus and Pseudo-nitzschia subcurvata) and Phaeocystis antarctica, three important phytoplankton species collected from the Ross Sea, to assess how temperature elevation and iron addition impact uptake rates of a number of inorganic and organic carbon, nitrogen, and phosphorus substrates. These culture studies generally show that when temperature is increased, diatoms are able to take up nutrients more rapidly than Phaeocystis antarctica. Results from this dissertation show that nutrient cycles and phytoplankton communities in the Southern California Bight and the Ross Sea, Antarctica will likely be different in the future. Although all variables tested were found to exert some influence on microbial nutrient cycling, temperature elevation generally had the largest effect, increasing biomass and uptake rates, structuring the composition of the microbial community, and altering stoichiometry. This research did not include top down effects and it is limited spatially and temporally, however, it demonstrates the importance of studying different nutrient substrates and looking at multiple interactive stressors to gain a more comprehensive view of potential change.

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Chaud, Luciana Cristina Silveira. "Estabelecimento de condições de cultivo de leveduras isoladas na Antártica visando à produção de proteases". Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/97/97132/tde-07112014-160203/.

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Micro-organismos oriundos de ecossistemas restritivos e pouco explorados como o continente Antártico têm despertado grande interesse na comunidade científica, visto que pesquisas biotecnológicas podem resultar em produtos de alto valor agregado. Dentre estes produtos, enzimas de psicrófilos ou psicrotolerantes, que apresentam alta atividade catalítica aliada à flexibilidade, estimulam a busca de condições que favoreçam a sua produção. Assim, as proteases se destacam neste universo, visto que respondem por cerca de 60% do mercado mundial de enzimas. Neste contexto, o objetivo do presente trabalho foi o de selecionar, dentre os isolados de diferentes amostras do continente Antártico, leveduras produtoras destas enzimas, bem como de estabelecer condições de cultivo laboratorial para o favorecimento da atividade proteolítica. Foram utilizadas 99 leveduras previamente isoladas na Divisão de Recursos Microbianos da Coleção Brasileira de Micro-organismos de Ambiente e Indústria da UNICAMP, das quais 14,14% (n= 14) foram selecionadas como produtoras de proteases por meio de ensaios em placas contendo ágar Sabouraud com leite desnatado (10%). O perfil da atividade proteolítica extracelular, o crescimento e o consumo de açúcar das leveduras selecionadas foram avaliados a partir do cultivo das mesmas em caldo Sabouraud, pH 5,5, a 150rpm, a 25°C por 120h. Todos os isolados selecionados mostraram alguma atividade proteolítica em meio líquido. A levedura Rhodotorula mucilaginosa L07 foi então selecionada para a etapa seguinte, em função da máxima atividade proteolítica (33,36 U.mL-1) observada em meio líquido. Para avaliar o impacto da suplementação do meio de cultivo e da variação de parâmetros físico-químicos sobre a atividade proteolítica desta levedura, e ainda visando o favorecimento da produção de proteases, foi utilizado o planejamento fatorial fracionado 26-2, seguido de planejamento fatorial completo (DCCR 23). Os resultados obtidos permitiram estabelecer um modelo matemático que foi validado, elevando a atividade proteolítica inicial em 45,53%. A caracterização da protease produzida por R. mucilaginosa L07 revelou seu caráter ácido, cuja máxima atividade (71,14 U.ml-1) foi obtida em pH 5,0 a 50°C. Verificou-se ainda que 70% da atividade proteolítica foi conservada quando os ensaios foram realizados a 37°C e 80% em 45 e 60°C. Esta enzima mostrou-se altamente estável após incubação por 1h em temperaturas até 50°C, verificando-se a manutenção da atividade proteolítica. Estas características combinadas com a atividade proteolítica sugerem que esta protease exibe potencial para ser utilizada em processos biotecnológicos.
Microorganisms from restrictive and unexplored ecosystems as the Antarctic continent have been of great interest in the scientific community, because they can synthesize biotechnological products with high added value. Among these products, psychrotolerants or psychrophilic enzymes, which present high activity coupled with flexibility, stimulates the studies regarding to optimize conditions in order to favor their production. Proteases are highlighted in this universe, because that account for about 60 % of the enzymes world market. In this context, the aim of this work was to select among microorganisms strains isolated from Antarctica, specifically protease-producing yeast, as well as establishing its growth conditions at laboratory scale focusing on its proteolytic activity. Ninety-nine previously isolated yeasts (DRM CPQBA / UNICAMP), from different samples of the Antarctic continent were evaluated and 14,14% (n = 14) were selected as protease producers in Sabouraud Agar containing skim milk (10%). The profile of the extracellular proteolytic activity, growth conditions and sugar consumption by selected yeast strains was reported in Sabouraud broth at pH 5.5, agitation rate of 150 rpm, 25 ° C for 120h. The results showed that all selected strains presented proteolytic activity. The maximum activity values was observed with Rhodotorula mucilaginosa L07 (33,36 U.mL-1), which was selected to continue the experiments. In the next step it was studied the effect of nutrients supplementation of the culture medium and the variation of physicochemical parameters on the proteolytic activity of R. mucilaginosa L07 by using an experimental design consisting of 26-2 fractional factorial followed by a full factorial design (CCRD 23). The results obtained allowed to stablish a mathematical model, which was validated, allowing the increase of the initial proteolytic activity in 45.53%. Characterization of protease produced by R. mucilaginosa L07 showed an acid character, and a maximum activity of 71.14 U.ml-1 was obtained at pH 5.0 at 50°C. It was also found that 70% of the proteolytic activity was preserved when the assays were performed at 37°C and 80% at 45 and 60°C. This enzyme was highly stable after incubation at temperatures <= 50°C/ 1 h, maintaining the proteolytic activity. These characteristics combined with enzymatic activity, suggests that this protease exhibits potential use in biotechnological processes.

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Mills, Sarah Victoria. "Novel biochemical compounds from Antarctic microorganisms". Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342463.

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O'Brien, Andrea C. "Cold active antimicrobial compounds from Antarctic microorganisms". Thesis, London South Bank University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288169.

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Burke, Genola. "The molecular identification and evaluation of the effects of cold temperatures on Antarctic Pseudomonas spp". Birmingham, Ala. : University of Alabama at Birmingham, 2009. https://www.mhsl.uab.edu/dt/2009m/burke.pdf.

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Jungblut, Anne Dorothee Biotechnology &amp Biomolecular Sciences Faculty of Science UNSW. "Characterisation of microbial Mat communities in meltwater ponds of the McMurdo ice shelf, Antarctica". 2007. http://handle.unsw.edu.au/1959.4/40496.

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The investigation presented in this thesis examined the microbial and functional diversity of the meltwater ponds Fresh, Orange and Salt Ponds on the McMurdo Ice Shelf, near Bratina Island, Antarctica. These sites were chosen because of the ecological importance and absence of detailed characterisations of their diversity and function as part of Antarctica?s largest wetland. Particular focus was on cyanobacterial diversity, nitrogen fixation and secondary metabolite production. Using 16S rRNA gene and morphological analysis a large diversity of cyanobacteria (more than 22 phylotypes) was identified with high phylogenetic similarities (up to 99% sequence identity) to cyanobacteria from mats in other regions of Antarctica. In addition biogeographical distributions were identified including potentially endemic and cosmopolitan cyanobacteria. High salinities were also connected to the change and reduction of diversity. Lipid marker analyses were performed targeting hydrocarbons, ether-linked hydrocarbons, methylated fatty acid esters (FAME), wax esters, hopanols and sterols. Lipid biomarker profiles were similar to typical cyanobacteria dominated mats with major input from microorganisms including oxygenic and anoxygenic phototrophs, obligate aerobic and anaerobic heterotrophs that conduct the metabolic processes of fermentation, sulphate reduction, sulphate and iron-oxidation, methanogeneses. Signature lipids indicative of Chloroflexus and archaea, as well as branched aliphatic alkanes with quaternary substituted carbon atoms (BAQCs), were identified for the first time in Fresh, Orange and Salt Ponds. Based on nifH gene analysis, the nitrogen fixing diversity characterised in Orange Pond consisted of cyanobacterial Nostoc sp. as well as firmicutes, beta-, gamma- and delta-proteobacteria. Acetylene reduction assays and nifH gene RNA transcript diversity identified Nostoc sp. as a main contributor of nitrogenase activity in these ponds. Furthermore, analytical methods were used to identify the cyanobacterial secondary metabolites microcystins, although the genetic basis for this production and the toxin producer could not been identified. However non-ribosomal peptide synthetases (NRPS) and polyketide synthases (PKS) genes were identified which could be the genetic basis for novel bioactives. The use of a multi-disciplinary approach synthesis and subsequent results significantly increased our understanding of the diversity and function of microbial mat communities in the unique meltwater ponds of the McMurdo Ice shelf, Antarctica.

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Libri sul tema "Microorganisms – Antarctica"

Polar microbiology: The ecology, biodiversity, and bioremediation potential of microorganisms in extremely cold environments. Boca Raton: Taylor & Francis, 2010.

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Pavón Oro, Alequis Tomás. Efecto proapoptótico y antimetastásico en líneas tumorales humanas colorrectales de una proteína secretada por la bacteria Rizosférica Antártica Bacillus sp. K2I17. Universidad Autónoma de Chile, 2019. http://dx.doi.org/10.32457/20.500.12728/87432019dcbm4.

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El cáncer es la segunda causa de muerte en el mundo, y específicamente en Chile el cáncer colorrectal es el único que presenta un aumento sostenido de la mortalidad en la última década. La búsqueda de nuevos agentes quimioterapeúticos anticancerígenos ha propuesto a los microorganismos extremófilos como una fuente potencial para obtener moléculas citotóxicas, que induzcan apoptosis en las células tumorales. Las condiciones extremas del continente antártico y las presiones selectivas por el espacio y los nutrientes que se producen entre los microorganismos del rizobioma de la planta Deschampsia antarctica Desv sugirieron como hipótesis que las bacterias rizosféricas aisladas en la Antártica secretan al sobrenadante de cultivo moléculas bioactivas que inhiben la invasión y proliferación de líneas tumorales humanas de origen colorrectal mediante un mecanismo apoptótico. En este sentido, el objetivo general del trabajo fue identificar y caracterizar a moléculas bioactivas con acción antinvasiva y antiproliferativa, además, determinar el mecanismo inhibitorio de la proliferación en líneas tumorales humanas de origen colorrectal. Los resultados del primer objetivo específico demostraron que los sobrenadantes de cultivo de los aislados rizosféricos antárticos K2 y MI disminuyeron la viabilidad de la línea celular de adenocarcinoma colorrectal LoVo en el ensayo de reducción metabólica del MTT. Además, como los sobrenadantes no tuvieron efecto en la viabilidad de las bacterias E. coli y Staphylococcus aureus, y tampoco en los hongos unicelulares Candida albicans y Saccharomyces cerevisiae, el resultado indicó que la actividad antiproliferativa fue selectiva hacia la línea celular LoVo.

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Capitoli di libri sul tema "Microorganisms – Antarctica"

Boyd, William L., James T. Staley e Josephine W. Boyd. "Ecology of Soil Microorganisms of Antarctica". In Antarctic Soils and Soil Forming Processes, 125–59. Washington, D. C.: American Geophysical Union, 2013. http://dx.doi.org/10.1029/ar008p0125.

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King-Miaow, Katie, Kevin Lee, Teruya Maki, Donnabella LaCap-Bugler e Stephen David James Archer. "Airborne Microorganisms in Antarctica: Transport, Survival and Establishment". In Springer Polar Sciences, 163–96. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-02786-5_8.

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Franzmann, P. D. "The Microbiota of Saline Lakes of the Vestfold Hills, Antarctica". In General and Applied Aspects of Halophilic Microorganisms, 9–14. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4615-3730-4_2.

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Gomez, Fiorella F., Jaime D. Babot, Gustavo A. Lovrich, Faustino Siñeriz e Osvaldo Delgado. "Microorganisms from Patagonia and Antarctica and Their Cold-Active Skills for Using Polymeric Materials". In Biology and Biotechnology of Patagonian Microorganisms, 155–67. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-42801-7_10.

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Onofri, Silvano. "Antarctic Microfungi". In Enigmatic Microorganisms and Life in Extreme Environments, 323–36. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4838-2_26.

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Bölter, Manfred, e Ellen Kandeler. "Microorganisms and Microbial Processes in Antarctic Soils". In Cryosols, 557–72. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-662-06429-0_27.

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Giménez, Matías, Gastón Azziz, Paul R. Gill e Silvia Batista. "Horizontal Gene Transfer Elements: Plasmids in Antarctic Microorganisms". In Springer Polar Sciences, 85–107. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-02786-5_5.

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Yarzábal, Luis Andrés. "Antarctic Psychrophilic Microorganisms and Biotechnology: History, Current Trends, Applications, and Challenges". In Microbial Models: From Environmental to Industrial Sustainability, 83–118. Singapore: Springer Singapore, 2016. http://dx.doi.org/10.1007/978-981-10-2555-6_5.

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Abyzov, S. S., M. N. Poglazova, J. N. Mitskevich e M. V. Ivanov. "Chapter 16. Common Features of Microorganisms in Ancient Layers of the Antarctic Ice Sheet". In Life in Ancient Ice, a cura di John D. Castello e Scott O. Rogers, 240–50. Princeton: Princeton University Press, 2005. http://dx.doi.org/10.1515/9781400880188-020.

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Nakai, Ryosuke, Satoshi Imura e Takeshi Naganuma. "Patterns of Microorganisms Inhabiting Antarctic Freshwater Lakes with Special Reference to Aquatic Moss Pillars". In Springer Polar Sciences, 25–43. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-02786-5_2.

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Atti di convegni sul tema "Microorganisms – Antarctica"

Abyzov, Sabit S., Irina N. Mitskevich, Margarita N. Poglazova, Richard B. Hoover e Mikhail V. Ivanov. "Microorganisms and unicellular algae in the ice sheet of Antarctica". In SPIE's International Symposium on Optical Science, Engineering, and Instrumentation, a cura di Richard B. Hoover. SPIE, 1999. http://dx.doi.org/10.1117/12.375075.

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Mojib, Nazia, Asim K. Bej e Richard Hoover. "Diversity and cold adaptation of microorganisms isolated from the Schirmacher Oasis, Antarctica". In Optical Engineering + Applications, a cura di Richard B. Hoover, Gilbert V. Levin, Alexei Y. Rozanov e Paul C. Davies. SPIE, 2008. http://dx.doi.org/10.1117/12.795394.

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Abyzov, Sabit S., Irina N. Mitskevich, Margarita N. Poglazova, Nartsiss I. Barkov, Vladimir Y. Lipenkov, Nikita E. Bobin, Boris B. Koudryashov e Victor M. Pashkevich. "Long-term conservation of viable microorganisms in the ice sheet of Central Antarctica". In SPIE's International Symposium on Optical Science, Engineering, and Instrumentation, a cura di Richard B. Hoover. SPIE, 1998. http://dx.doi.org/10.1117/12.319824.

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Zhang, Hongyan, Shoko Hosoi-Tanabe, Shinichi Nagata, Syuhei Ban e Satoshi Imura. "Cultivation and Characterization of Microorganisms in Antarctic Lakes". In OCEANS 2008 - MTS/IEEE Kobe Techno-Ocean. IEEE, 2008. http://dx.doi.org/10.1109/oceanskobe.2008.4531040.

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VanCleave, Samantha Ashley. "CHARACTERIZATION OF EPS PRODUCING MICROORGANISMS IN ANTARCTIC SUBGLACIAL SYSTEMS". In 67th Annual Southeastern GSA Section Meeting - 2018. Geological Society of America, 2018. http://dx.doi.org/10.1130/abs/2018se-312267.

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Mitskevich, Irina N., Margarita N. Poglazova e Sabit S. Abyzov. "Study of the microorganisms preserved in the Central Antarctic glacier in connection with the problems of astrobiology". In Instruments, Methods, and Missions for Astrobiology V, a cura di Richard B. Hoover, Alexei Y. Rozanov e Jere H. Lipps. SPIE, 2003. http://dx.doi.org/10.1117/12.486689.

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