Microbe-mediated co-oxidation mechanism of As and Sb and its environmental services

As and Sb are both toxic metalloids co-occurred in the environments and were identified with elevated concentrations in mine tailings. Microorganisms played an important role for biogeochemical cycling of As and Sb, which substantially influence the fate and transport of As and Sb in the environments. Microbial-mediated As(III) and Sb(III) oxidation has important environmental implications because they can reduce the toxicity and mobility of As and Sb. In this study, bacteria responsible for As(III)- and Sb(III)-oxidation were identified by DNA-SIP. It has long been thought that microorganisms used similar metabolic pathways to transform As and Sb. In this study, we tested such hypothesis but identified that functional bacteria in this mine tailings may use different pathways to oxidize As(III) and Sb(III). Further, As(III)- and Sb(III)-oxidizing bacteria were isolated from the enrichment cultures and were used to investigate the microbial mechanisms for As(III) and Sb(III) oxidation. Finally, the environmental services (e.g., nitrogen fixation, phosphate dissolution, and plant growth promotion) provided by biotic As(III) and Sb(III) oxidation were investigated.