# 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.

## Key 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.