Extremophiles: Dry Environments (including Cryptoendoliths)

Nienow, James A.

doi:10.1016/b978-012373944-5.00277-7

Cited by 24 publications

(11 citation statements)

References 6 publications

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“…3g). These aggregates cannot be classified as hypoliths (lower [base] surface of a stone in association with adherent soil particles sensu Nienow, 2009), since they occupy the bottom surface of the crusts but inhabit inside of the crust. These aggregates are described in more detail in the following sections.…”

Section: Resultsmentioning

confidence: 99%

“…These observations would explain why in the hyperarid core of the Atacama Desert calcium sulfate crusts are preferentially colonized by epilithic lichens and endolithic algae associated with fungi that are adapted to the extremely dry and hot environment. Imbibition time (in hours per year of daylight when lichens are moist) has been used as an indicator of the distribution of lichens and endolithic micro‐organisms biodiversity in the Negev Desert (Danin & Garty, 1983; Nienow, 2009). According to the last author if the conditions results in more than 450 h of daylight imbibition time epilithic lichens dominate, between 300 and 450 h of imbibition euendolithic lichens dominate, and at lower levels the free‐living euendolithic fungus Lichenothelia dominate in loose association with cryptoendolithic and chasmoendolithic cyanobacteria and eukaryotic algae.…”

Section: Discussionmentioning

confidence: 99%

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Microbial colonization of Ca-sulfate crusts in the hyperarid core of the Atacama Desert: implications for the search for life on Mars

Wierzchoś¹,

Cámara²,

Rı́os³

et al. 2010

Geobiology

148

123

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The scarcity of liquid water in the hyperarid core of the Atacama Desert makes this region one of the most challenging environments for life on Earth. The low numbers of microbial cells in the soils suggest that within the Atacama Desert lies the dry limit for life on our planet. Here, we show that the Ca-sulfate crusts of this hyperarid core are the habitats of lithobiontic micro-organisms. This microporous, translucent substrate is colonized by epilithic lichens, as well as endolithic free-living algae, fungal hyphae, cyanobacteria and non photosynthetic bacteria. We also report a novel type of endolithic community, "hypoendoliths", colonizing the undermost layer of the crusts. The colonization of gypsum crusts within the hyperarid core appears to be controlled by the moisture regime. Our data shows that the threshold for colonization is crossed within the dry core, with abundant colonization in gypsum crusts at one study site, while crusts at a drier site are virtually devoid of life. We show that the cumulative time in 1 year of relative humidity (RH) above 60% is the best parameter to explain the difference in colonization between both sites. This is supported by controlled humidity experiments, where we show that colonies of endolithic cyanobacteria in the Ca-sulfate crust undergo imbibition process at RH >60%. Assuming that life once arose on Mars, it is conceivable that Martian micro-organisms sought refuge in similar isolated evaporite microenvironments during their last struggle for life as their planet turned arid.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Microbial colonization of Ca-sulfate crusts in the hyperarid core of the Atacama Desert: implications for the search for life on Mars

Wierzchoś¹,

Cámara²,

Rı́os³

et al. 2010

Geobiology

148

123

View full text Add to dashboard Cite

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“…In these ecosystems, phototrophic-based communities develop inside translucent rock substrates. The susceptibility of rocks to endolithic colonization depends mainly on the physical and chemical properties of the substrate (Nienow, 2009). These properties are essential to provide the microbial community with enough light for photosynthesis, appropriate moisture retention from water collection during rain or fog events, a heat sink and reflector to help regulate temperature, and protection against harmful UV radiation (Friedmann and Ocampo-Friedmann, 1984;Nienow, 2009;Wierzchos et al, 2012a).…”

Section: Introductionmentioning

confidence: 99%

Microbial diversity and the presence of algae in halite endolithic communities are correlated to atmospheric moisture in the hyper‐arid zone of the Atacama Desert

Robinson

Wierzchos

Black

et al. 2014

Environmental Microbiology

101

168

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The Atacama Desert is one of the oldest and driest deserts in the world, and its hyper-arid core is described as 'the most barren region imaginable'. We used a combination of high-throughput sequencing and microscopy methods to characterize the endolithic microbial assemblages of halite pinnacles (salt rocks) collected in several hyper-arid areas of the desert. We found communities dominated by archaea that relied on a single phylotype of Halothece cyanobacteria for primary production. A few other phylotypes of salt-adapted bacteria and archaea, including Salinibacter, Halorhabdus, and Halococcus were major components of the halite communities, indicating specific adaptations to the unique halite environments. Multivariate statistical analyses of diversity metrics clearly separated the halite communities from that of the surrounding soil in the Yungay area. These analyses also revealed distribution patterns of halite communities correlated with atmospheric moisture. Microbial endolithic communities from halites exposed to coastal fogs and high relative humidity were more diverse; their archaeal and bacterial assemblages were accompanied by a novel algae related to oceanic picoplankton of the Mamiellales. In contrast, we did not find any algae in the Yungay pinnacles, suggesting that the environmental conditions in this habitat might be too extreme for eukaryotic photosynthetic life.

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“…These evaporitic rocks are colonized by endolithic (rock interior in the sense of Golubic et al . [] and Nienow []) microbial communities [ Wierzchos et al ., ; de los Ríos et al ., ] (Figure b). The dynamics of water vapor within the pinnacles in response to air relative humidity have been studied previously using environmental sensors [ Davila et al ., ; Wierzchos et al ., ].…”

Section: Methodsmentioning

confidence: 99%

Application of artificial neural networks as a tool for moisture prediction in microbially colonized halite in the Atacama Desert

et al. 2015

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The Atacama Desert is the driest and one of the most life-limiting places on Earth. Despite the extreme conditions, microbial endolithic communities have been found inside halite rocks. The presence of these microbial communities is possible due to the hygroscopic properties of evaporitic rocks composed of sodium chloride. It is important to elucidate every possible water source in such a hyperarid environment. Therefore, in the present study, an artificial neural network (ANN) based model has been designed to predict the presence of liquid water on the surface of halite pinnacles. The model predicts the moisture formation using two basic meteorological variables, air temperature, and air relative humidity. ANNs have been successfully employed for the first time as a tool for predicting the appearance of liquid water, a key factor for the endolithic microbial communities living in the driest part of the Atacama Desert. The model developed is able to correctly predict the formation of water on the surface of the halite pinnacles 83% of the cases. We anticipate the future application of this model as an important tool for the prediction of the water availability and therefore potential habitability of lithic substrates in extreme environments on Earth and perhaps elsewhere.

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Extremophiles: Dry Environments (including Cryptoendoliths)

Cited by 24 publications

References 6 publications

Microbial colonization of Ca-sulfate crusts in the hyperarid core of the Atacama Desert: implications for the search for life on Mars

Microbial colonization of Ca-sulfate crusts in the hyperarid core of the Atacama Desert: implications for the search for life on Mars

Microbial diversity and the presence of algae in halite endolithic communities are correlated to atmospheric moisture in the hyper‐arid zone of the Atacama Desert

Application of artificial neural networks as a tool for moisture prediction in microbially colonized halite in the Atacama Desert

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