Desulfurivibrio spp. drives sulfur-oxidizing Sb(V) reduction process in antimony contaminated regions. mine drainage metagenome

Antimony (Sb) contamination released from mine tailings is a severe environmental threat to both the local ecosystem and exposed human populations. In Sb-associated mine tailings, the S- and Sb- rich geochemical conditions may promote specific biogeochemical processes. In the current study, a novel biogeochemical Sb cycling, i.e., S-oxidizing Sb(V) reduction, was observed in the cultures inoculated from Sb mine tailings. Bacteria associated with the genus Desulfurivibrio were identified as the S-oxidizing Sb(V) reducing bacteria (S-oxidizing SbRB) by stable isotope probing. The retrieved metagenome assembled genome (MAG) revealed that the Desulfurivibrio-associated MAG possesses necessary genes for Sb(V) reduction and S oxidation, which further confirmed its role as S-oxidizing SbRB. Other genetic evidence demonstrated its potential contribution to the ecosystem by carbon fixation, nitrogen fixation, and phosphate acquisition. Investigation of environmental samples from Sb mining impacted regions suggested Desulfurivibrio constituted a significant fraction of the tailing microbial community, but not in other Sb contaminated environments (i.e. adjacent soils, paddies, and river sediments). Panmetagenomic analysis revealed the ability to couple S-oxidation and Sb(V) reduction was a conserved genetic trait for Desulfurivibrio residing in metal-contaminated sites in southern China. The identification of putative S-oxidizing SbRB provided a possible management strategy to reduce Sb's environmental impact in the future.