Cloning of an organophosphorus hydrolase (opdD) gene of Lactobacillus sakei WCP904 isolated from chlorpyrifos-impregnated kimchi and hydrolysis activities of its gene product for organophosphorus pesticides

Abstract

Chlorpyrifos (CP) residues are absorbed from soil and often found in Korean cabbages that are being used to make kimchi. Lactobacillus sakei WCP904, harboring the organophosphorus (OP) hydrolase gene opdD, was isolated from CP-impregnated mulkimchi. The cloned gene opdD from strain CP904 comprises 825 base-pair nucleotides that encode 274 amino acids. The recombinant Escherichia coli harboring the opdD gene depleted 73% of CP after 6days in M9 medium. In fact, the OpdD protein is a novel member of the GHSQG family of esterolytic enzymes or lactic acid bacterial Opd groups. The molecular weight of the OpdD protein was estimated to be 31kDa using SDS-PAGE. Broad-spectrum activities of the OpdD protein were obtained against OP insecticides containing both P-O and P-S bonds. The OpdD protein exhibits maximum activity at 30 degrees C with pH 6. No enzyme activities of the mutated OpdD (Ser116Ala116) protein toward -nitrophenyl butyrate and CP substrates were observed. These results suggested that the strain WCP904 scavenges insecticide residues from mulkimchi vegetables, thus abolishing health hazards by secreting OP hydrolase during fermentation.