Demethylation of the Antibiotic Methylarsenite is Coupled to Denitrification in Anoxic Paddy Soil

• DOI: 10.1021/acs.est.1c04167
• Publication Date: 2021-11-03T12:32:11Z
• Authors: Chuan Chen; Yang Shen; Yuanhe Li; Wenwen Zhang; Fang-Jie Zhao
• Keywords: Demethylation

Arsenic (As) biomethylation is an important component of the As biogeochemical cycle, which produces methylarsenite [MAs(III)] as intermediate product. Its high toxicity used by some microbes antibiotic to kill off other and gain a competitive advantage. Some aerobic have evolved detoxification mechanism demethylate MAs(III) via dioxygenase C–As lyase ArsI. How demethylated under anoxic conditions unclear. We found that nitrate addition flooded paddy soil enhanced demethylation. A facultative anaerobe Bacillus sp. CZDM1 isolated from was able nitrate-reducing conditions. putative gene (BcarsI) identified in genome strain CZDM1. The expression BcarsI As-sensitive Escherichia coli AW3110 conferred bacterium ability condition its resistance MAs(III). Both E. harboring could not fermentative Five conserved amino acid resides cysteine, histidine, glutamic are essential for demethylation Putative arsI genes widely present denitrifying bacteria, with 75% sequenced genomes containing arsI, also possessing dissimilatory reductase narG or napA. These results reveal novel ArsI coupling denitrification, such likely be common environment soils wetlands.