Drivers of Diversity for Microbial Communities Inhabiting Halites from 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”. Under these extreme moisture, thermal, and solar radiation stress, habitats inside halite pinnacles harbour flourishing microbial communities. We use a combination of high-throughput sequencing and microscopy methods to characterize the microbial assemblages of halites collected in several areas of the desert. We found communities dominated by Archaea and relying 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 and revealed a distribution patterns of halite communities strongly correlated to atmospheric moisture. Communities from halites exposed to costal fogs were more diverse than halites from the Yungay area, in both their archaeal and bacterial assemblages, and were colonized 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 at the limit for eukaryotic life.