Metabolic potential of newly isolated bacterial species from the deep subsurface of the Iberian Pyrite Belt

Río Tinto (Huelva, Spain) is an extreme environment whose origin is a natural underground bioreactor in which the high concentration of metallic sulfides of the Iberian Pyrite Belt are dissolved by microbial activity. As part of a drilling project conducted in the source area of the river, several microorganisms were isolated under strict anaerobic conditions from the deep subsurface of this ecosystem. Here, we report the genomic analysis of these isolates to assess their role in the bioreactor. We sequenced and assembled the genomes of twelve new isolates and studied the potential role of thirteen native microorganisms in the biogeochemical cycles operating in the deep subsurface of the Iberian Pyrite Belt. Our results indicate that seven of the microorganisms belong to new species. Several isolates encode genes associated with metabolic functions relevant for the subsurface bioreactor, including H 2 production and carbon fixation. In addition, three isolates have the potential to synthesize vitamin B 12 , which could be essential to maintain the microbial community in this ecosystem. Finally, certain genera seem to be highly adapted and widely distributed in the deep subsurface of the Iberian Pyrite Belt.