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Jacek Wierzchos - One of the best experts on this subject based on the ideXlab platform.
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Response of endolithic Chroococcidiopsis strains from the polyextreme Atacama Desert to light radiation
2020Co-Authors: María Cristina Casero, Carmen Ascaso, Antonio Quesada, Hanna Mazur-marzec, Jacek WierzchosAbstract:The Atacama Desert is known to be the place on Earth with one of the highest solar radiation limiting the presence of life to endolithic microhabitats and soil microbial ecosystems. Endolithic microbial communities are supported by photosynthetic primary producers, mainly cyanobacteria, which can be injured by UVR. Nevertheless, cyanobacteria exposed to high solar radiation and its harmful effects have developed a series of defense mechanisms: avoidance, antioxidant systems or production of photoprotective compounds such as scytonemin among others. Scytonemin is a liposoluble pigment whose absorption maxima are located in UVA and UVC range and highly absorbing in the UVB range. In order to elucidate the protection capacity of endolithic cyanobacteria against harmful radiation, two cyanobacterial strains from Chroococcidiopsis genus were isolated from different endolithic microhabitats in the Atacama Desert: UAM813 strain, originally from the cryptoendolithic microhabitat of halite (NaCl), and UAM816 strain from chasmoendolithic microhabitat of calcite (CaCO3). Both were exposed to PAR and UVR+PAR conditions studying their short-term response, as oxidative stress and long-term response, as scytonemin production, metabolic activity and ultrastructural damage. The observed response of both strains reveals a high sensitivity to direct light exposure, even to PAR. The differences in their acclimation suggest specific adaptation strategies related to their original microhabitat, revealing their protective potential and the strain specific environmental pressure selection to inhabit different microhabitats and exposed to different light conditions.
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Preandean Atacama Desert Endolithic Microbiology
Microbial Ecosystems in Central Andes Extreme Environments, 2020Co-Authors: María Cristina Casero, Jacek Wierzchos, Victoria Meslier, Jocelyne DiruggieroAbstract:Endolithic ecosystems are considered environmental refuges for life in arid and hyperarid Deserts around the world. The microbial communities colonizing these habitats are of special interest due to their ability to live in a polyextreme environment characterized by scarcity of water and extreme solar radiation. The Preandean Depression of the Atacama Desert harbors a number of these endolithic ecosystems, where various substrates are colonized by rich and diverse communities of phototrophic and heterotrophic microorganisms. Recent studies revealed that these communities are dominated by Cyanobacteria, Actinobacteria, Proteobacteria, and Chloroflexi phyla. Studies of the photosynthetic primary producers demonstrated their essential role in supporting the community and uncovered unique adaptation strategies against extreme solar radiation. The diversity found in the endolithic communities of the Preandean Depression, both at the phylogenetic and functional levels, was found to be strongly dependent on water availability and associated with the specific architecture of the substrate. This chapter describes the composition, functioning, and adaptation strategies of microbial communities inhabiting the endolithic substrates found in the Preandean zone of the Atacama Desert. We address the principal biotic and abiotic drivers explaining their diversity from a multidisciplinary perspective.
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Endolithic microbial habitats as refuges for life in polyextreme environment of the Atacama Desert.
Current opinion in microbiology, 2018Co-Authors: Jacek Wierzchos, María Cristina Casero, Octavio Artieda, Carmen AscasoAbstract:The extremely harsh conditions of hyperarid Deserts are a true challenge for microbial life. Microorganisms thriving in such polyextreme environments are fascinating as they can tell us more about life, its strategies and its boundaries than other groups of organisms. The Atacama Desert (North Chile) holds two world records of extreme environmental characteristics: the lowest rainfall and greatest surface ultraviolet radiation and total solar irradiance ever measured on Earth. Despite these limiting conditions for life, we recently identified several remarkable examples of endolithic habitats colonized by phototrophic and heterotrophic microorganisms in the hyperarid core of the Atacama Desert.
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in situ metabolism in halite endolithic microbial communities of the hyperarid Atacama Desert
Frontiers in Microbiology, 2015Co-Authors: Alfonso F Davila, Carmen Ascaso, Jocelyne Diruggiero, Ian Hawes, Jonathan G Araya, Diego R Gelsinger, Anne Osano, Jacek WierzchosAbstract:The Atacama Desert of northern Chile is one of the driest regions on Earth, with areas that exclude plants and where soils have extremely low microbial biomass. However, in the driest parts of the Desert there are microorganisms that colonize the interior of halite nodules in fossil continental evaporites, where they are sustained by condensation of atmospheric water triggered by the salt substrate. Using a combination of in situ observations of variable chlorophyll fluorescence and controlled laboratory experiments, we show that this endolithic community is capable of carbon fixation both through oxygenic photosynthesis and potentially ammonia oxidation. We also present evidence that photosynthetic activity is finely tuned to moisture availability and solar insolation and can be sustained for days, and perhaps longer, after a wetting event. This is the first demonstration of in situ active metabolism in the hyperarid core of the Atacama Desert, and it provides the basis for proposing a self-contained, endolithic community that relies exclusively on non-rainfall sources of water. Our results contribute to an increasing body of evidence that even in hyperarid environments active metabolism, adaptation, and growth can occur in highly specialized microhabitats.
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Salt deliquescence drives photosynthesis in the hyperarid Atacama Desert
Environmental microbiology reports, 2013Co-Authors: Alfonso F Davila, Carmen Ascaso, Ian Hawes, Jacek WierzchosAbstract:Summary Endolithic cyanobacteria are found in halite nodules in the hyperarid core of the Atacama Desert. Using Pulse Amplitude Modulated Fluorometry, we show here that photosynthetic systems of these cyanobacteria become active when the relative humidity rises above 70% and the salt becomes wet by way of deliquescence. This is the first evidence of active metabolism in the hyperarid core of the Atacama, and supports the view of a microbial community sustained by deliquescence. Our results expand the water activity envelope of life on Earth.
Alfonso F Davila - One of the best experts on this subject based on the ideXlab platform.
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in situ metabolism in halite endolithic microbial communities of the hyperarid Atacama Desert
Frontiers in Microbiology, 2015Co-Authors: Alfonso F Davila, Carmen Ascaso, Jocelyne Diruggiero, Ian Hawes, Jonathan G Araya, Diego R Gelsinger, Anne Osano, Jacek WierzchosAbstract:The Atacama Desert of northern Chile is one of the driest regions on Earth, with areas that exclude plants and where soils have extremely low microbial biomass. However, in the driest parts of the Desert there are microorganisms that colonize the interior of halite nodules in fossil continental evaporites, where they are sustained by condensation of atmospheric water triggered by the salt substrate. Using a combination of in situ observations of variable chlorophyll fluorescence and controlled laboratory experiments, we show that this endolithic community is capable of carbon fixation both through oxygenic photosynthesis and potentially ammonia oxidation. We also present evidence that photosynthetic activity is finely tuned to moisture availability and solar insolation and can be sustained for days, and perhaps longer, after a wetting event. This is the first demonstration of in situ active metabolism in the hyperarid core of the Atacama Desert, and it provides the basis for proposing a self-contained, endolithic community that relies exclusively on non-rainfall sources of water. Our results contribute to an increasing body of evidence that even in hyperarid environments active metabolism, adaptation, and growth can occur in highly specialized microhabitats.
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Colonization patterns of soil microbial communities in the Atacama Desert
Microbiome, 2013Co-Authors: Alexander Crits-christoph, Christopher P. Mckay, Alfonso F Davila, Courtney K. Robinson, Tyler P. Barnum, W. Florian Fricke, Bruno Jedynak, Jocelyne DiruggieroAbstract:The Atacama Desert is one of the driest Deserts in the world and its soil, with extremely low moisture, organic carbon content, and oxidizing conditions, is considered to be at the dry limit for life. Analyses of high throughput DNA sequence data revealed that bacterial communities from six geographic locations in the hyper-arid core and along a North-South moisture gradient were structurally and phylogenetically distinct (ANOVA test for observed operating taxonomic units at 97% similarity (OTU0.03), P
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colonization patterns of soil microbial communities in the Atacama Desert
Microbiome, 2013Co-Authors: Alexander Critschristoph, Christopher P. Mckay, Alfonso F Davila, Courtney K. Robinson, Tyler P. Barnum, Bruno Jedynak, Florian W Fricke, Jocelyne DiruggieroAbstract:The Atacama Desert is one of the driest Deserts in the world and its soil, with extremely low moisture, organic carbon content, and oxidizing conditions, is considered to be at the dry limit for life. Analyses of high throughput DNA sequence data revealed that bacterial communities from six geographic locations in the hyper-arid core and along a North-South moisture gradient were structurally and phylogenetically distinct (ANOVA test for observed operating taxonomic units at 97% similarity (OTU0.03), P <0.001) and that communities from locations in the hyper-arid zone displayed the lowest levels of diversity. We found bacterial taxa similar to those found in other arid soil communities with an abundance of Rubrobacterales, Actinomycetales, Acidimicrobiales, and a number of families from the Thermoleophilia. The extremely low abundance of Firmicutes indicated that most bacteria in the soil were in the form of vegetative cells. Integrating molecular data with climate and soil geochemistry, we found that air relative humidity (RH) and soil conductivity significantly correlated with microbial communities’ diversity metrics (least squares linear regression for observed OTU0.03 and air RH and soil conductivity, P <0.001; UniFrac PCoA Spearman’s correlation for air RH and soil conductivity, P <0.0001), indicating that water availability and salt content are key factors in shaping the Atacama soil microbiome. Mineralization studies showed communities actively metabolizing in all soil samples, with increased rates in soils from the southern locations. Our results suggest that microorganisms in the driest soils of the Atacama Desert are in a state of stasis for most of the time, but can potentially metabolize if presented with liquid water for a sufficient duration. Over geological time, rare rain events and physicochemical factors potentially played a major role in selecting micro-organisms that are most adapted to extreme desiccating conditions.
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Salt deliquescence drives photosynthesis in the hyperarid Atacama Desert
Environmental microbiology reports, 2013Co-Authors: Alfonso F Davila, Carmen Ascaso, Ian Hawes, Jacek WierzchosAbstract:Summary Endolithic cyanobacteria are found in halite nodules in the hyperarid core of the Atacama Desert. Using Pulse Amplitude Modulated Fluorometry, we show here that photosynthetic systems of these cyanobacteria become active when the relative humidity rises above 70% and the salt becomes wet by way of deliquescence. This is the first evidence of active metabolism in the hyperarid core of the Atacama, and supports the view of a microbial community sustained by deliquescence. Our results expand the water activity envelope of life on Earth.
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microbial colonization of halite from the hyper arid Atacama Desert studied by raman spectroscopy
Philosophical Transactions of the Royal Society A, 2010Co-Authors: Petr Vitek, Carmen Ascaso, Howell G M Edwards, Jan Jehlicka, A De Los Rios, Sergio Valea, Susana E Jorgevillar, Alfonso F Davila, Jacek WierzchosAbstract:The hyper-arid core of the Atacama Desert (Chile) is the driest place on Earth and is considered a close analogue to the extremely arid conditions on the surface of Mars. Microbial life is very rar...
Rosa B. Scorzelli - One of the best experts on this subject based on the ideXlab platform.
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Weathering of ordinary chondrites from the Atacama Desert, Chile, by Mössbauer spectroscopy and synchrotron radiation X-ray diffraction
Meteoritics & Planetary Science, 2013Co-Authors: P. Munayco, J. Munayco, M. Valenzuela, Pierre Rochette, Jérôme Gattacceca, Roberto R. De Avillez, Rosa B. ScorzelliAbstract:Some terrestrial areas have climatic and geomorphologic features that favor the preservation, and therefore, accumulation of meteorites. The Atacama Desert in Chile is among the most important of such areas, known as DCA. This Desert is the driest on Earth, one of the most arid, uninhabitable localities with semiarid, arid, and hyper-arid conditions. The meteorites studied here were collected from within the DCA of San Juan and Pampa de Mejillones, located, respectively, in the Central Depression and the Coastal Range of the Atacama Desert. 57Fe Mossbauer spectroscopy was used for quantitative analysis of the degree of weathering of the meteorites, through the determination of the proportions of the various Fe-bearing phases and in particular the amount of oxidized iron in terrestrial alteration products. The abundance of ferric ions in weathered chondrites can be related to specific precursor compositions and to the level of terrestrial weathering. The aim of the study was the identification, quantification, and differentiation of the weathering products in the ordinary chondrites found in the San Juan and the Pampa de Mejillones areas of the Atacama Desert. The 57Fe Mossbauer spectroscopy study was complemented by synchrotron radiation X-ray diffraction and magnetic susceptibility measurements. The results allow a clear differentiation of the rate of weathering in meteorite samples collected from the San Juan versus the Pampa de Mejillones areas of the Atacama Desert.
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57Fe Mössbauer spectroscopy studies of chondritic meteorites from the Atacama Desert, Chile: Implications for weathering processes
LACAME 2012, 2013Co-Authors: P. Munayco, J. Munayco, M. Valenzuela, Pierre Rochette, Jérôme Gattacceca, Rosa B. ScorzelliAbstract:Some terrestrial areas have climatic and geomorphologic features that favor the preservation, and therefore, accumulation of meteorites. The Atacama Desert in Chile is among the most important of such areas, known as dense collection areas. This Desert is the driest on Earth, one of the most arid, uninhabitable locals with semi-arid, arid and hyper-arid conditions. The meteorites studied here were collected from within the dense collection area of San Juan at the Central Depression and Coastal Range of Atacama Desert. 57Fe Mossbauer spectroscopy was used for quantitative analysis of the degree of weathering of the meteorites, through the determination of the proportions of the various Fe-bearing phases and in particular the amount of oxidized iron in the terrestrial alteration products. The abundance of ferric ions in weathered chondrites can be related to specific precursor compositions and to the level of terrestrial weathering. The aim of the study was the identification, quantification and differentiation of the weathering products in the ordinary chondrites found in the San Juan area of Atacama Desert.
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57 Fe Mössbauer spectroscopy studies of chondritic meteorites from the Atacama Desert, Chile: Implications for weathering processes
Hyperfine Interactions, 2013Co-Authors: P. Munayco, J. Munayco, M. Valenzuela, Pierre Rochette, Jérôme Gattacceca, Rosa B. ScorzelliAbstract:Some terrestrial areas have climatic and geomorphologic features that favor the preservation, and therefore, accumulation of meteorites. The Atacama Desert in Chile is among the most important of such areas, known as dense collection areas. This Desert is the driest on Earth, one of the most arid, uninhabitable locals with semi-arid, arid and hyper-arid conditions. The meteorites studied here were collected from within the dense collection area of San Juan at the Central Depression and Coastal Range of Atacama Desert. 57Fe Mossbauer spectroscopy was used for quantitative analysis of the degree of weathering of the meteorites, through the determination of the proportions of the various Fe-bearing phases and in particular the amount of oxidized iron in the terrestrial alteration products. The abundance of ferric ions in weathered chondrites can be related to specific precursor compositions and to the level of terrestrial weathering. The aim of the study was the identification, quantification and differentiation of the weathering products in the ordinary chondrites found in the San Juan area of Atacama Desert.
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57 Fe Mössbauer spectroscopy studies of chondritic meteorites from the Atacama Desert, Chile: Implications for weathering processes
Hyperfine Interactions, 2013Co-Authors: P. Munayco, J. Munayco, M. Valenzuela, Pierre Rochette, Jérôme Gattacceca, Rosa B. ScorzelliAbstract:Some terrestrial areas have climatic and geomorphologic features that favor the preservation, and therefore, accumulation of meteorites. The Atacama Desert in Chile is among the most important of such areas, known as dense collection areas. This Desert is the driest on Earth, one of the most arid, uninhabitable locals with semi-arid, arid and hyper-arid conditions. The meteorites studied here were collected from within the dense collection area of San Juan at the Central Depression and Coastal Range of Atacama Desert. [superscript 57]Fe Mössbauer spectroscopy was used for quantitative analysis of the degree of weathering of the meteorites, through the determination of the proportions of the various Fe-bearing phases and in particular the amount of oxidized iron in the terrestrial alteration products. The abundance of ferric ions in weathered chondrites can be related to specific precursor compositions and to the level of terrestrial weathering. The aim of the study was the identification, quantification and differentiation of the weathering products in the ordinary chondrites found in the San Juan area of Atacama Desert
Carmen Ascaso - One of the best experts on this subject based on the ideXlab platform.
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Response of endolithic Chroococcidiopsis strains from the polyextreme Atacama Desert to light radiation
2020Co-Authors: María Cristina Casero, Carmen Ascaso, Antonio Quesada, Hanna Mazur-marzec, Jacek WierzchosAbstract:The Atacama Desert is known to be the place on Earth with one of the highest solar radiation limiting the presence of life to endolithic microhabitats and soil microbial ecosystems. Endolithic microbial communities are supported by photosynthetic primary producers, mainly cyanobacteria, which can be injured by UVR. Nevertheless, cyanobacteria exposed to high solar radiation and its harmful effects have developed a series of defense mechanisms: avoidance, antioxidant systems or production of photoprotective compounds such as scytonemin among others. Scytonemin is a liposoluble pigment whose absorption maxima are located in UVA and UVC range and highly absorbing in the UVB range. In order to elucidate the protection capacity of endolithic cyanobacteria against harmful radiation, two cyanobacterial strains from Chroococcidiopsis genus were isolated from different endolithic microhabitats in the Atacama Desert: UAM813 strain, originally from the cryptoendolithic microhabitat of halite (NaCl), and UAM816 strain from chasmoendolithic microhabitat of calcite (CaCO3). Both were exposed to PAR and UVR+PAR conditions studying their short-term response, as oxidative stress and long-term response, as scytonemin production, metabolic activity and ultrastructural damage. The observed response of both strains reveals a high sensitivity to direct light exposure, even to PAR. The differences in their acclimation suggest specific adaptation strategies related to their original microhabitat, revealing their protective potential and the strain specific environmental pressure selection to inhabit different microhabitats and exposed to different light conditions.
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Endolithic microbial habitats as refuges for life in polyextreme environment of the Atacama Desert.
Current opinion in microbiology, 2018Co-Authors: Jacek Wierzchos, María Cristina Casero, Octavio Artieda, Carmen AscasoAbstract:The extremely harsh conditions of hyperarid Deserts are a true challenge for microbial life. Microorganisms thriving in such polyextreme environments are fascinating as they can tell us more about life, its strategies and its boundaries than other groups of organisms. The Atacama Desert (North Chile) holds two world records of extreme environmental characteristics: the lowest rainfall and greatest surface ultraviolet radiation and total solar irradiance ever measured on Earth. Despite these limiting conditions for life, we recently identified several remarkable examples of endolithic habitats colonized by phototrophic and heterotrophic microorganisms in the hyperarid core of the Atacama Desert.
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in situ metabolism in halite endolithic microbial communities of the hyperarid Atacama Desert
Frontiers in Microbiology, 2015Co-Authors: Alfonso F Davila, Carmen Ascaso, Jocelyne Diruggiero, Ian Hawes, Jonathan G Araya, Diego R Gelsinger, Anne Osano, Jacek WierzchosAbstract:The Atacama Desert of northern Chile is one of the driest regions on Earth, with areas that exclude plants and where soils have extremely low microbial biomass. However, in the driest parts of the Desert there are microorganisms that colonize the interior of halite nodules in fossil continental evaporites, where they are sustained by condensation of atmospheric water triggered by the salt substrate. Using a combination of in situ observations of variable chlorophyll fluorescence and controlled laboratory experiments, we show that this endolithic community is capable of carbon fixation both through oxygenic photosynthesis and potentially ammonia oxidation. We also present evidence that photosynthetic activity is finely tuned to moisture availability and solar insolation and can be sustained for days, and perhaps longer, after a wetting event. This is the first demonstration of in situ active metabolism in the hyperarid core of the Atacama Desert, and it provides the basis for proposing a self-contained, endolithic community that relies exclusively on non-rainfall sources of water. Our results contribute to an increasing body of evidence that even in hyperarid environments active metabolism, adaptation, and growth can occur in highly specialized microhabitats.
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Salt deliquescence drives photosynthesis in the hyperarid Atacama Desert
Environmental microbiology reports, 2013Co-Authors: Alfonso F Davila, Carmen Ascaso, Ian Hawes, Jacek WierzchosAbstract:Summary Endolithic cyanobacteria are found in halite nodules in the hyperarid core of the Atacama Desert. Using Pulse Amplitude Modulated Fluorometry, we show here that photosynthetic systems of these cyanobacteria become active when the relative humidity rises above 70% and the salt becomes wet by way of deliquescence. This is the first evidence of active metabolism in the hyperarid core of the Atacama, and supports the view of a microbial community sustained by deliquescence. Our results expand the water activity envelope of life on Earth.
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microbial colonization of halite from the hyper arid Atacama Desert studied by raman spectroscopy
Philosophical Transactions of the Royal Society A, 2010Co-Authors: Petr Vitek, Carmen Ascaso, Howell G M Edwards, Jan Jehlicka, A De Los Rios, Sergio Valea, Susana E Jorgevillar, Alfonso F Davila, Jacek WierzchosAbstract:The hyper-arid core of the Atacama Desert (Chile) is the driest place on Earth and is considered a close analogue to the extremely arid conditions on the surface of Mars. Microbial life is very rar...
Christopher P. Mckay - One of the best experts on this subject based on the ideXlab platform.
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Colonization patterns of soil microbial communities in the Atacama Desert
Microbiome, 2013Co-Authors: Alexander Crits-christoph, Christopher P. Mckay, Alfonso F Davila, Courtney K. Robinson, Tyler P. Barnum, W. Florian Fricke, Bruno Jedynak, Jocelyne DiruggieroAbstract:The Atacama Desert is one of the driest Deserts in the world and its soil, with extremely low moisture, organic carbon content, and oxidizing conditions, is considered to be at the dry limit for life. Analyses of high throughput DNA sequence data revealed that bacterial communities from six geographic locations in the hyper-arid core and along a North-South moisture gradient were structurally and phylogenetically distinct (ANOVA test for observed operating taxonomic units at 97% similarity (OTU0.03), P
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colonization patterns of soil microbial communities in the Atacama Desert
Microbiome, 2013Co-Authors: Alexander Critschristoph, Christopher P. Mckay, Alfonso F Davila, Courtney K. Robinson, Tyler P. Barnum, Bruno Jedynak, Florian W Fricke, Jocelyne DiruggieroAbstract:The Atacama Desert is one of the driest Deserts in the world and its soil, with extremely low moisture, organic carbon content, and oxidizing conditions, is considered to be at the dry limit for life. Analyses of high throughput DNA sequence data revealed that bacterial communities from six geographic locations in the hyper-arid core and along a North-South moisture gradient were structurally and phylogenetically distinct (ANOVA test for observed operating taxonomic units at 97% similarity (OTU0.03), P <0.001) and that communities from locations in the hyper-arid zone displayed the lowest levels of diversity. We found bacterial taxa similar to those found in other arid soil communities with an abundance of Rubrobacterales, Actinomycetales, Acidimicrobiales, and a number of families from the Thermoleophilia. The extremely low abundance of Firmicutes indicated that most bacteria in the soil were in the form of vegetative cells. Integrating molecular data with climate and soil geochemistry, we found that air relative humidity (RH) and soil conductivity significantly correlated with microbial communities’ diversity metrics (least squares linear regression for observed OTU0.03 and air RH and soil conductivity, P <0.001; UniFrac PCoA Spearman’s correlation for air RH and soil conductivity, P <0.0001), indicating that water availability and salt content are key factors in shaping the Atacama soil microbiome. Mineralization studies showed communities actively metabolizing in all soil samples, with increased rates in soils from the southern locations. Our results suggest that microorganisms in the driest soils of the Atacama Desert are in a state of stasis for most of the time, but can potentially metabolize if presented with liquid water for a sufficient duration. Over geological time, rare rain events and physicochemical factors potentially played a major role in selecting micro-organisms that are most adapted to extreme desiccating conditions.
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evidence of a microbial community associated with rock varnish at yungay Atacama Desert chile
Journal of Geophysical Research, 2008Co-Authors: Kimberly R Kuhlman, Parth Venkat, Myron T La Duc, Gregory M Kuhlman, Christopher P. MckayAbstract:[1] Rock varnish is a very slow-growing nanostratigraphic coating consisting of approximately 70% fine-grained clay and 30% iron and manganese oxides that forms on the surfaces of rocks in arid and semiarid climates. The microbial diversity associated with rock varnish collected from the hyperarid Yungay region of the Atacama Desert was investigated using culture-independent biomolecular methods and an adenosine triphosphate (ATP) assay. The extraction of DNA from rock varnish collected at Yungay, a region in which little to no DNA has been extracted from the surface soil (<1 cm) to date, indicates that rock varnish may provide a niche habitat for microbial life where water is essentially absent. The clone library constructed suggests the presence of numerous phylogenetically distinct microorganisms, ranging in diversity from Cyanobacterial to a-proteobacteria lineages. The findings also show that only a few micrometers of varnish material are enough to shelter microbes like Chroococcidiopsis spp. from the intense ultraviolet radiation present in the Atacama Desert. Whether or not microorganisms are involved in its nucleation and/or growth, rock varnish appears to provide a microhabitat resembling cryptoendolithic communities seen on a larger scale.
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A preliminary survey of non-lichenized fungi cultured from the hyperarid Atacama Desert of Chile.
Astrobiology, 2006Co-Authors: Catharine A. Conley, Galina Ishkhanova, Christopher P. Mckay, Ken CullingsAbstract:The Atacama Desert is one of the driest environments on Earth, and has been so for over 200,000 years. Previous reports have suggested that surprisingly low numbers of culturable bacteria, counted as biomass or species diversity, are present in Atacama sands collected from the most hyperarid regions. In previous studies, the presence of eukaryotic organisms was not discussed. In this report, we describe a method of direct plating onto rich media that resulted in culturing a range of fungi from Atacama samples. All fungi identified in this preliminary survey are spore-forming saprobes that are readily dispersed by wind, a likely mechanism that accounts for their presence in the central Atacama Desert.
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endolithic cyanobacteria in halite rocks from the hyperarid core of the Atacama Desert
Astrobiology, 2006Co-Authors: Jacek Wierzchos, Carmen Ascaso, Christopher P. MckayAbstract:In the driest parts of the Atacama Desert there are no visible life forms on soil or rock surfaces. The soil in this region contains only minute traces of bacteria distributed in patches, and conditions are too dry for cyanobacteria that live under translucent stones. Here we show that halite evaporite rocks from the driest part of the Atacama Desert are colonized by cyanobacteria. This colonization takes place just a few millimeters beneath the rock surface, occupying spaces among salt crystals. Our work reveals that these communities are composed of extremely resistant Chroococcidiopsis morphospecies of cyanobacteria and associated heterotrophic bacteria. This newly discovered endolithic environment is an extremely dry and, at the same time, saline microbial habitat. Photosynthetic microorganisms within dry evaporite rocks could be an important and previously unrecognized target for the search for life within our Solar System.