Screening, identification, and molecular mechanism study of strain transforming Roxarsone. Pseudomonas chlororaphis strain:YJSXZ-2023

Roxarsone is an arsenic-containing compound which widely used as organoarsenical feed additive. Roxentered into soils through excrements of livestock and further degrades to highly toxic arsenic species by microbial transformation. Here, we isolated a pure cultured Rox transforming bacterial strain, Pseudomonas chlororaphis, from an chicken feed soil. During Rox biotransformation by Pseudomonas chlororaphis, five metabolites including 3-amino-4-hydroxyphenylarsonic acid, N-acetyl-4-hydroxy-m-arsanilic acid , arsenate , arsenite, and dimethylarsenate were detected. The nitroreductase gene PcmdaB and the acetyltransferase gene PcnhoA were identified through the whole genome sequencing. We constructed the recombinant plasmids pET22b-PcmdaB and pET22b-PcnhoA, and identified they could catalyze nitroreduction and acetylation of roxarsone , respectively, both in vivo and in vitro. Our study screened a pure bacterium Pseudomonas chlororaphis in soil and identified the pathway of Rox transformation, and characterized the functional of nitroreductase gene PcmdaB and acetyltransferase gene PcnhoA in Pseudomonas chlororaphis, which expand the understanding of organicarsenic biogeochemistry cycle and provide theoretical basis for the treatment of organic arsenic contaminated soil.