Efficient Hydrolysis of Dichlorvos in Water by Stenotrophomonas acidaminiphila G1 and Methyl Parathion Hydrolase

TL;DR

A new bacteria strain and enzyme are found to quickly break down the pesticide dichlorvos, reducing its harmful effects.

Contribution

Discovery of Stenotrophomonas acidaminiphila G1 and the methyl parathion hydrolase enzyme for rapid DDVP degradation.

Findings

Strain G1 degrades dichlorvos to 20 mg/L with a DT50 of 3.81 minutes under optimal conditions.

Methyl parathion hydrolase (MPD) enzyme completely degrades 20 mg/L DDVP within 1 minute.

Dimethyl phosphate is the main non-toxic degradation product of dichlorvos.

Abstract

Dichlorvos (DDVP) has been used in the management of agricultural pests for a long time. DDVP can cause DNA damage in mammals, and its residues in the environment and food have attracted attention. In this study, we reported a DDVP-degrading strain, Stenotrophomonas acidaminiphila G1, which could degrade DDVP to 20 mg/L with a DT50 of 3.81 min at 37 °C, a pH of 7.0, and a concentration of 1.18 × 1010 colony-forming units (CFUs)/mL. Strain G1’s DDVP degradation products were determined by comparison with standard substances and UPLC-MS/MS analysis. The results showed that dimethyl phosphate (DMPP) was the main metabolite of DDVP, and its toxicity to non-target organisms was significantly lower than that of the parent compound. Furthermore, the key genes for the degradation of DDVP by strain G1 were analyzed using whole-genome sequencing. A methyl parathion hydrolase gene, mpd, was identified, and its activity was verified through prokaryotic expression and enzyme kinetics. The purified enzyme MPD could entirely degrade 20 mg/L DDVP within 1 min. These results not only provide biological resources for the rapid degradation of organophosphorus pesticides but also offer a theoretical basis for the efficient remediation of pesticide residues.

Figures