Rapid Biodegradation of the Organophosphorus Insecticide Chlorpyrifos by X1.

Chlorpyrifos was one of the most widely used organophosphorus insecticides and the neurotoxicity and genotoxicity of chlorpyrifos to mammals, aquatic organisms and other non-target organisms have caused much public concern. X1, a type of strain of the genus , is capable of efficiently degrading 200 mg/L of chlorpyrifos within 48 h. This is ~100 fold faster than B-14, a well-studied chlorpyrifos-degrading bacterial strain. Strain X1 can tolerate high concentrations (500 mg/L) of chlorpyrifos over a wide range of temperatures (30-42 °C) and pH values (5-9). RT-qPCR analysis showed that the organophosphorus hydrolase (OpdB) in strain X1 was an inducible enzyme, and the crude enzyme isolated in vitro could still maintain 75% degradation activity. Strain X1 can simultaneously degrade chlorpyrifos and its main hydrolysate 3,5,6-trichloro-2-pyridinol. TCP could be further metabolized through stepwise oxidative dechlorination and further opening of the benzene ring to be completely degraded by the tricarboxylic acid cycle. The results provide a potential means for the remediation of chlorpyrifos- contaminated soil and water.