Comparative analysis of cyanobacteria inhabiting rocks with different light transmittance in the Mojave Desert: a Mars terrestrial analogue

Smith, H. D.; Baqué, Mickaël; Duncan, A.; Lloyd, Christopher R.; McKay, Christopher P.; Billi, Daniela

doi:10.1017/s1473550414000056

Cited by 43 publications

(33 citation statements)

References 31 publications

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“…Cyanobacteria photosynthetic activity is essential for endolithic communities and, therefore, the light intensity and wavelengths reaching the colonization zone within the endolithic habitats could be a limiting factor (Nienow et al ., ; Boison et al ., ; Smith et al ., ; Raanan et al ., ). Extremely high solar fluxes were measured in the VL and MTQ locations (up to 2554 µmol photons m −2 s −1 ) but rock substrates have the capacity of drastically attenuating incident light and stopping harmful UV radiation (Berner and Evenari, ; Oren et al ., ; Matthes et al ., ; Hughes and Lawley, ; Horath et al ., ; Amaral et al ., ; Hall et al ., ; Cockell et al ., ; Cowan et al ., ; Smith et al ., ; Wierzchos et al ., ). The spectral data we obtained for our four rock substrates revealed that light transmission was inversely correlated with depth of colonization.…”

Section: Discussionmentioning

confidence: 97%

Fundamental drivers for endolithic microbial community assemblies in the hyperarid Atacama Desert

Meslier

Casero

Dailey

et al. 2018

Environmental Microbiology

102

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In hyperarid deserts, endolithic microbial communities colonize the rocks' interior as a survival strategy. Yet, the composition of these communities and the drivers promoting their assembly are still poorly understood. We analysed the diversity and community composition of endoliths from four different lithic substrates - calcite, gypsum, ignimbrite and granite - collected in the hyperarid zone of the Atacama Desert, Chile. By combining microscopy, mineralogy, spectroscopy and high throughput sequencing, we found these communities to be highly specific to their lithic substrate, although they were all dominated by the same four main phyla, Cyanobacteria, Actinobacteria, Chloroflexi and Proteobacteria. Our finding indicates a fine scale diversification of the microbial reservoir driven by substrate properties. The data suggest that the overall rock chemistry and the light transmission properties of the substrates are not essential drivers of community structure and composition. Instead, we propose that the architecture of the rock, i.e., the space available for colonization and its physical structure, linked to water retention capabilities, is ultimately the driver of community diversity and composition at the dry limit of life.

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Section: Discussionmentioning

confidence: 97%

Fundamental drivers for endolithic microbial community assemblies in the hyperarid Atacama Desert

Meslier

Casero

Dailey

et al. 2018

Environmental Microbiology

102

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“…These communities have been reported from many hot deserts including the Mojave (Schlesinger et al 2003;Smith et al 2014), Atacama (Warren-Rhodes et al 2006;Azúa-Bustos et al 2011;Lacap et al 2011), Negev (Friedmann et al 1967;Berner and Evenari 1978;Wierzchos et al 2012) and Namib (Stomeo et al 2013) and in other semiarid and hyperarid regions (Tracy et al 2010;Pointing et al 2007;Wong et al 2010;Weber et al 2013). …”

Section: Introductionmentioning

confidence: 91%

The spatial structures of hypolithic communities in the Dry Valleys of East Antarctica

2014

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Hypolithic communities represent important reservoirs of microbial life in hyper-arid deserts. A number of studies on the diversity and ecology of these communities from different geographic areas have been reported in the past decade, but the spatial distribution of the different components of these communities is still not understood. Moss-and cyanobacteria-dominated hypolithic communities morphotypes from Miers Valley (McMurdo Dry Valleys, East Antarctica) were analyzed by electron microscopy in order to characterize the micro-scale spatial structure. The two communities showed a high degree of internal organization, but differing according to the biological composition. In moss-dominated hypoliths, the moss plantlets are intermixed with mineral fragments of soil origin. However, in cyanobacteria-dominated hypoliths, a layered spatial organization was structured by filamentous cyanobacteria and associated extracellular polymeric components. While moss cells were lacking in cyanobacteria-dominated communities, biofilms formed by cyanobacteria and heterotrophic bacteria were observed in both community morphotypes. The waterholding capacity of both live and dead moss cells and the associated organic matrix, together with the protective properties of the extracellular polymeric substances, could facilitate the survival and activity of these communities. Similar structural strategies can favour the survival of microbial communities in different extreme environments.

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“…3B shows the green biofilm of cyanobacteria that live beneath translucent rocks in many deserts surviving on as little as a few days of rain or fog each year (32)(33)(34). The example shown is from an unusual carbonate rock from the Mojave Desert that is clear inside but covered with a red coating (35,36). Fig.…”

Section: Strategy For Exoplanetsmentioning

confidence: 99%

Requirements and limits for life in the context of exoplanets

McKay

2014

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

126

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The requirements for life on Earth, its elemental composition, and its environmental limits provide a way to assess the habitability of exoplanets. Temperature is key both because of its influence on liquid water and because it can be directly estimated from orbital and climate models of exoplanetary systems. Life can grow and reproduce at temperatures as low as −15°C, and as high as 122°C. Studies of life in extreme deserts show that on a dry world, even a small amount of rain, fog, snow, and even atmospheric humidity can be adequate for photosynthetic production producing a small but detectable microbial community. Life is able to use light at levels less than 10 −5 of the solar flux at Earth. UV or ionizing radiation can be tolerated by many microorganisms at very high levels and is unlikely to be life limiting on an exoplanet. Biologically available nitrogen may limit habitability. Levels of O 2 over a few percent on an exoplanet would be consistent with the presence of multicellular organisms and high levels of O 2 on Earth-like worlds indicate oxygenic photosynthesis. Other factors such as pH and salinity are likely to vary and not limit life over an entire planet or moon.extremophiles | Mars | astrobiology T he list of exoplanets is increasing rapidly with a diversity of masses, orbital distances, and star types. The long list motivates us to consider which of these worlds could support life and what type of life could live there. The only approach to answering these questions is based on observations of life on Earth. Compared with astronomical targets, life on Earth is easily studied and our knowledge of it is extensive--but it is not complete. The most important area in which we lack knowledge about life on Earth is its origin. We have no consensus theory for the origin of life nor do we know the timing or location (1). What we do know about life on Earth is what it is made of, and we know its ecological requirements and limits. Thus, it is not surprising that most of the discussions related to life on exoplanets focus on the requirements for life rather than its origin. In this paper we follow this same approach but later return briefly to the question of the origin of life. Limits to LifeThere are two somewhat different approaches to the question of the limits of life. The first approach is to determine the requirements for life. The second approach is to determine the extreme environments in which adapted organisms-often referred to as extremophiles-can survive. Both perspectives are relevant to the question of life on exoplanets.It is useful to categorize the requirements for life on Earth as four items: energy, carbon, liquid water, and various other elements. These are listed in Table 1 along with the occurrence of these factors in the Solar System (2). In our Solar System it is the occurrence of liquid water that appears to limit the occurrence of habitable environments and this appears to be the case for exoplanetary systems as well.From basic thermodynamic considerations it is clear that life ...

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Comparative analysis of cyanobacteria inhabiting rocks with different light transmittance in the Mojave Desert: a Mars terrestrial analogue

Cited by 43 publications

References 31 publications

Fundamental drivers for endolithic microbial community assemblies in the hyperarid Atacama Desert

Fundamental drivers for endolithic microbial community assemblies in the hyperarid Atacama Desert

The spatial structures of hypolithic communities in the Dry Valleys of East Antarctica

Requirements and limits for life in the context of exoplanets

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