Biodegradable properties of organophosphorus insecticides by the potential probiotic Lactobacillus plantarum WCP931 with a degrading gene (opdC)

Abstract

An organophosphorus (OP) insecticide-mineralizing strain, Lactobacillus plantarum WCP931, harboring a new OP hydrolase (opdC) gene, was isolated during kimchi (Korean traditional food) fermentation. Strain WCP931 exhibited a significant survival rate of 51 to 96% under artificial gastric acid conditions at pH 2 to 3 after 3 h. The opdC gene, consisting of 831 bp encoding 276 amino acids, was cloned from strain WCP907. Recombinant Escherischia coli harboring the opdC gene depleted 77% chlorpyrifos (CP) in M9 minimal medium after 6 days of incubation. The OpdC enzyme represents a novel member of the GHSQG family of esterolytic enzymes or a new Opd group. The OpdC molecular mass was estimated to be approximately 31 kDa by SDS-PAGE and showed maximum activity at pH 6 and 35 degrees C. The mutated OpdC (Ser116 -> Ala116) enzyme had no activity towards OP insecticides and rho-nitrophenol-beta-butyrate. Importantly, the relative activity of OpdC protein against chlorpyrifos, coumafos, diazinon, fenamifos, methyl parathion, and parathion was higher than that against cadosafos, dyfonate, and ethoprofos insecticides. These results suggested the involvement of OpdC in the biodegradation of OP insecticide-contaminated cabbage during fermentation. The new OpdC enzyme expands the heterogeneity of the lactic acid bacterial Opd enzyme group in nature.