Raman imaging of microbial colonization in rock-some analytical aspects.

Raman imaging allows one to obtain spatially resolved chemical information in a nondestructive manner. Herein, we present analytical aspects of effective in situ and in vivo Raman imaging of algae and cyanobacteria from within their native rock habitats. Specifically, gypsum and halite inhabited by endolithic communities from the hyperarid Atacama Desert were analyzed.

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

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.

Endolithic microbial habitats as refuges for life in polyextreme environment of the Atacama Desert.

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.

Discovery of carotenoid red-shift in endolithic cyanobacteria from the Atacama Desert.

The biochemical responses of rock-inhabiting cyanobacteria towards native environmental stresses were observed in vivo in one of the Earth's most challenging extreme climatic environments. The cryptoendolithic cyanobacterial colonization, dominated by Chroococcidiopsis sp., was studied in an ignimbrite at a high altitude volcanic area in the Atacama Desert, Chile.

Raman imaging in geomicrobiology: endolithic phototrophic microorganisms in gypsum from the extreme sun irradiation area in the Atacama Desert.

The Raman imaging method was successfully applied for mapping the distribution of biomolecules (e.g., pigments) associated with cryptoendolithic and hypoendolithic microorganisms, as well as the inorganic host mineral matrix that forms the habitat for the biota.

Phylogenetic and Functional Substrate Specificity for Endolithic Microbial Communities in Hyper-Arid Environments.

Under extreme water deficit, endolithic (inside rock) microbial ecosystems are considered environmental refuges for life in cold and hot deserts, yet their diversity and functional adaptations remain vastly unexplored. The metagenomic analyses of the communities from two rock substrates, calcite and ignimbrite, revealed that they were dominated by Cyanobacteria, Actinobacteria, and Chloroflexi. The relative distribution of major phyla was significantly different between the two substrates and biodiversity estimates, from 16S rRNA gene sequences and from the metagenomic data, all pointed to a higher taxonomic diversity in the calcite community.

Adaptation strategies of endolithic chlorophototrophs to survive the hyperarid and extreme solar radiation environment of the Atacama Desert.

The Atacama Desert, northern Chile, is one of the driest deserts on Earth and, as such, a natural laboratory to explore the limits of life and the strategies evolved by microorganisms to adapt to extreme environments. Here we report the exceptional adaptation strategies of chlorophototrophic and eukaryotic algae, and chlorophototrophic and prokaryotic cyanobacteria to the hyperarid and extremely high solar radiation conditions occurring in this desert. Our approach combined several microscopy techniques, spectroscopic analytical methods, and molecular analyses.

Ignimbrite textural properties as determinants of endolithic colonization patterns from hyper-arid Atacama Desert.

This study explores the photosynthetic microbial colonization of rhyolitic ignimbrites in Lomas de Tilocalar, a hyper-arid region of the Atacama Desert, Chile. Colonization appeared in the form of a green layer a few millimeters beneath the ignimbrite surface. Some ignimbrite rocks revealed two distinct micromorphological areas of identical mineralogical and chemical composition but different textural properties.

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.

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.