Diazinon degradation by a novel strain Ralstonia sp. DI-3 and X-ray crystal structure determination of the metabolite of diazinon.

Diazinon is a widely used organophosphorus insecticide often detected in the environment. A highly effective diazinon-degrading Ralstonia sp. strain DI-3 was isolated from agricultural soil. Strain DI-3 can utilize dimethoate as its sole carbon source for growth and degrade an initial concentration of 100 mg L-1 diazinon to non-detectable levels within 60 h in liquid culture. A small amount of second carbon source as co-substrate could slightly enhance the biodegradation of diazinon. In addition, a less toxic metabolic intermediate formed during the degradation of diazinon mediated by strain DI-3 was purified using thin-layer chromatography (TLC) and identified based on single-crystal Xray diffraction analysis, allowing a degradation pathway for diazinon by pure culture to be proposed. Finally, this is the first providing authentic evidence to describe the metabolite.