Biogeographical patterns of bacterial and archaeal communities of distant hypersaline environments

Microorganisms are globally distributed, however new evidences show that the microbial structure of the communities can vary due to their geographical location and environmental parameters. We analyzed 50 samples including brines and sediments from Europe, Africa and South America applying the Operational Phylogenetic Unit (OPU) approach in order to understand whether microbial community structures in hypersaline environments exhibit biogeographical patterns. The fine-tuned identification of about 1000 OPUs (nearly equivalent to “species”) using multivariant analysis revealed regionally distinct taxa compositions. This segregation was more diffuse at genus level pointing to a phylogenetic and metabolic redundancy at higher taxa level, where their different species acquired distinct advantages related to the regional physicochemical idiosyncrasies. We also evidenced the presence of groups not previously described in such environments as Parcubacteria, or the presence of members of Nanohaloarchaeota in anaerobic hypersaline sediments. Finally, we observed an important OPU overlap between anoxic sediments and their overlaying brines, pointing to a versatile metabolism of the pelagic organisms.