LAUSR

Organophosphorus insecticides (OPs) have been widely used to control agricultural pests, which has raised concerns about OPs residues in crops and the environment. In this study, we investigated the degradation kinetics and pathways of 8 OPs by Cupriavidus nantongensis X1T and identified the enzyme via gene cloning and in vitro assays. The degradation half-life of methyl parathion, triazophos and phoxim was only 5 min, 9 min and 43 min, respectively. It was 46 fold faster than that of triazophos by Bacillus sp. TAP-1, a well-studied triazophos-degrader. Strain X1T completely degraded not only chlorpyrifos, methyl parathion, parathion, fenitrothion, triazophos and phoxim at 50 mg/L within 48 h, but also the phenolic metabolites. This was the fastest degradation of OPs by bacterial-whole cells reported so far. The OPs were first hydrolyzed by an OP hydrolase encoded by opdB gene in strain X1T, followed by further degradation of the metabolites. The crude enzyme maintained a full activity.