Biology of Desert Endolithic Habitats

Rock structure drives the taxonomic and functional diversity of endolithic microbial communities in extreme environments

“…The metagenomic comparison of gypsum endolithic communities from a hyper‐arid system provided, for the first time, the opportunity to characterize the taxonomic and functional level adaptations of these communities to their unique micro‐habitats. We found that the overall taxonomic composition of all gypsum communities was similar to that of previously reported endolithic communities from hyper‐arid deserts around the world and included Cyanobacteria , as the main primary producers, along with Actinobacteria , Proteobacteria , Chloroflexi , and Deinococcus (Dong et al ., 2007; Stivaletta et al ., 2010; Wierzchos et al ., 2015; Crits‐Christoph et al ., 2016b; Meslier et al ., 2018; Qu et al ., 2020a, 2020b). However, the low amino acid identity (AAI) of the gypsum MAGs to their closest characterized relatives revealed the genetic diversity of these communities and substantially expanded the genomic landscape that exists in hyper‐arid ecosystems.…”

“…Both eukaryotic groups were more abundant and more diverse in KM, which received higher amount of atmospheric water, while they were only sporadically detected in CL and MTQ. These results are in agreement with previous findings in gypsum and other endolithic systems, suggesting a dry limit for eukaryotic life (Robinson et al ., 2015; Wierzchos et al ., 2011, 2015; Qu et al ., 2020a, 2020b). Interestingly, no other substrate than gypsum has been shown to harbour fungi in the hyper‐arid Atacama Desert, which might be linked to the higher water absorption capacity of this substrate (Wierzchos et al ., 2011).…”

“…Endolithic (within rock) microbial communities inhabit the interiors of different types of translucent substrates, differing in terms of their mineral composition and porosity, such as halite, calcite, ignimbrite, granite, gypsum, and sandstone (for recent reviews, see Meslier and DiRuggiero, 2019; Qu et al ., 2020b). These communities are constituted of Cyanobacteria , and sometimes algae, as primary producers, and an assortment of heterotrophic taxa including Actinobacteria , Proteobacteria , Chloroflexi , Deinococcus , and haloarchaea in the case of halite (Walker and Pace, 2007; Robinson et al ., 2015; Crits‐Christoph et al ., 2016b; Meslier et al ., 2018).…”