ena-STUDY-LINNAEUS UNIVERSITY-12-11-2020-18:21:16:537-374
Connectivity of terrestrial deep biosphere microbial communities  with surface communities
The deep biosphere is one of the largest biomes on earth and contains viable organisms from all three domains of life. An unresolved question is if extremely nutrient poor deep terrestrial biosphere communities are shaped by infiltration of allochthonous surface microorganisms or if autochthonous species have evolved. In this study, analysis of 16S rRNA gene amplicon datasets showed that few surface microbes infiltrated to deep biosphere groundwaters, but these few populations constituted a significant fraction of the total microbial abundances. The observation that many deep biosphere populations lacked surface biome representatives suggest that they evolved from autochthonous populations. Interrogation of assembled genomes of abundant deep biosphere representatives identified a variety of metabolic strategies including sulfur cycling via oxidation by the SOX complex plus reduction via the reverse Wood-Ljungdahl pathway. In conclusion, these deep communities were a selection of infiltrated and indigenous populations adapted to the anoxic and low energy conditions.
The deep biosphere is one of the largest biomes on earth and contains viable organisms from all three domains of life. An unresolved question is if extremely nutrient poor deep terrestrial biosphere communities are shaped by infiltration of allochthonous surface microorganisms or if autochthonous species have evolved. In this study, analysis of 16S rRNA gene amplicon datasets showed that few surface microbes infiltrated to deep biosphere groundwaters, but these few populations constituted a significant fraction of the total microbial abundances. The observation that many deep biosphere populations lacked surface biome representatives suggest that they evolved from autochthonous populations. Interrogation of assembled genomes of abundant deep biosphere representatives identified a variety of metabolic strategies including sulfur cycling via oxidation by the SOX complex plus reduction via the reverse Wood-Ljungdahl pathway. In conclusion, these deep communities were a selection of infiltrated and indigenous populations adapted to the anoxic and low energy conditions.