Bacteria responsible for nitrate-dependent antimonite oxidation in antimony-contaminated paddy soil revealed by the combination of DNA-SIP and metagenomics

Antimonite (Sb(III)) oxidation (SbO) can decrease the toxicity of antimony (Sb) and its uptake into rice, thus serving an ecological role in bioremediation Sb contamination rice paddies decreasing translocation accumulation rice. Nitrate as electron acceptor be coupled to SbO anoxic environments, which, however, has not been reported paddy soils. Here we investigate potential for nitrate-dependent Sb-contaminated identify Sb(III)-oxidizing bacteria (SbOB) using stable isotope probing (SIP) with amplicon shotgun metagenomic sequencing. Anaerobic was exclusively observed soil amended both Sb(III) NO3?, whereas no apparent detected only. The increasing abundance arsenite oxidase gene (aioA) suggests that catalysed by microorganisms harbouring aioA gene. After 60-day DNA-SIP incubation, obvious shift relative heavy DNA fractions occurred only treatment 13C–NaHCO3, suggesting incorporation 13C SbOB. Accordingly, a number putative SbOB were identified soil, including Azoarcus, Azospira Chelativorans. Metagenomic analysis further revealed they contained genes involved denitrification carbon fixation, supporting their capability SbO. These observations suggested occurrence A (i.e., Chelativorans) here, which expands our current knowledge regarding diversity In addition, this study provides proof concept