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 °C. The mutated OpdC (Ser116 → Ala116) enzyme had no activity towards OP insecticides and ρ-nitrophenol-β-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.
Highlights
Pesticide-contaminated vegetables are more frequently ingested by humans in developing countries
The chlorpyrifos-degrading WCP931 strain was named as Lactobacillus plantarum WCP931
Several classes of esterase are revealed; among them, some are capable of degrading OP insecticides
Summary
Pesticide-contaminated vegetables are more frequently ingested by humans in developing countries. Vegetables are the most common foodstuff, and people consume 150–250 g of vegetables daily in Asian countries. In a major advance in 2018, Hwang and Moon [2] surveyed the levels of chlorpyrifos (CP) in Korean cabbage crops and detected 0.12–0.75 mg/kg of CP after 32–35 days of treatment. This research outcome led to anxiety among Korean citizens about consuming fermented food kimchi made from Chinese cabbage. Considerable attention must be paid to using organophosphate pesticides when cultivating Chinese cabbage plants, and pesticide residue avails in fermented kimchi should be monitored. The most striking result emerged that the LAB strains could use OP insecticides as a source of carbon and phosphorus in a defined medium and decontaminate vegetable insecticides used in mulkimchi fermentation [3]
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