Investigation of microbial activity hotspots in one of the most arid deserts of the world, specifically in lithic microhabitats of the Atacama Desert in Chile. For the first time, usage of a DNA separation approach, together with metagenomics and other analysis methods (i/e ATP, PLFA and metabolite analysis) to specifically gain insights on the living and potentially active microbial community.. Intracellular/Extracellular DNA and Metagenomic Characterization of Lithic Microhabitats in the Atacama Desert

The existence of microbial activity hotspots in temperate regions of Earth is driven by soil heterogeneities, especially the temporal and spatial availability of nutrients. Here we investigate whether microbial activity hotspots also exist in one of the most arid deserts of the world, specifically in lithic microhabitats of the Atacama Desert in Chile. While previous studies evaluated the total DNA fraction to elucidate on the microbial communities, we here for the first time use a DNA separation approach, together with metagenomics and other analysis methods (i/e ATP, PLFA and metabolite analysis) to specifically gain insights on the living and potentially active microbial community. Our results show that the hypolith colonized rocks are microbial hotspots in the desert environment. In contrast, our data does not support such a conclusion for the gypsum crust and salt rock environments, because only limited microbial activity could be observed. The hypolith community is dominated by phototrophs, mostly Cyanobacteria and Chloroflexi, at both study sites. The gypsum crusts are dominated by methylotrophs and heterotrophic phototrophs, mostly Chloroflexi, and the salt rocks (halite nodules) by halotolerant and phototrophic endoliths, mostly Cyanobacteria and Archaea. Major environmental constrains in the organic-poor arid and hyperarid Atacama Desert are water availability and protection from UV irradiation allowing phototrophs and other extremophiles to play a key role in desert ecology.