Copper stimulates neonicotinoid insecticide thiacloprid degradation by Ensifer adhaerens TMX‐23

摘要

Abstract Aims Aims of this study are to elucidate the molecular mechanism of copper‐improved thiacloprid (THI) degradation by Ensifer adhaerens TMX‐23 and characterize copper resistance of this strain. Methods and Results Resting cells of E. adhaerens TMX‐23 were used to degrade THI, with formation of THI amide and 98·31% of 0·59 mmol l−1 THI was degraded in 100 min. The addition of copper improved the degradation of THI and showed little inhibitory effects on the growth of E. adhaerens TMX‐23. E. adhaerens TMX‐23 degraded THI to THI amide by nitrile hydratases (NhcA and NhpA). QPCR analysis indicated that the expression of nhpA was up‐regulated in the presence of copper. E. adhaerens TMX‐23 nitrile hydratases were purified, and enzyme assay of NhpA exhibited the highest NHase activity toward THI. The addition of copper activated the activity of NhcA. Soil degradation experiment indicated that E. adhaerens TMX‐23 could quickly eliminate THI residual in copper‐added soil. Conclusions Copper improved THI degradation by E. adhaerens TMX‐23 was attributed to the induced expression of nhpA and activated NhcA. Significance and Impact of the Study This study broadens the investigation of regulatory mechanism of NHase expression and provided theoretical basis for using metal‐resistant microbes to degrade pesticide in heavy metal co‐contaminated environments.