Biodegradation of organophosphorus insecticides by two organophosphorus hydrolase genes (opdA and opdE) from isolated Leuconostoc mesenteroides WCP307 of kimchi origin

초록

This study is aimed to reveal the molecular incidence of organophosphorus insecticides degradation during the fermentation of Korean food yeulmu-mulkimchi. To this end, two opdA and opdE which consist of 930 and 894 bp that encode 309 and 297 amino acids, respectively, were cloned from the Leuconostoc mesenteroides WCP307 strain that was isolated from chlorpyrifos (CP) impregnated kimchi. The Escherichia coli that harbored the opdA and opdE genes depleted a CP concentration of 72% and 83%, respectively, in an M9 medium after 6 days. The OpdA and OpdE enzymes molecular weights were estimated to be approximately 35 and 33 kDa and showed optimal activities at 30 degrees C with a pH of 7.0 and 6.0, respectively. However, the mutated OpdA (Ser128 -> Ala128) and OpdE (Ser129 -> Ala129) enzymes had no activities on OP insecticides and p-nitrophenyl butyrate substrates. In addition, the OpdA and OpdE enzymes showed profound catalytic activities against cadusafos, comnaphos, diazinon, dyfonate, ethoprophos, fenamiphos, methylparathion, and parathion insecticides. Therefore, it is assumed that OpdA and OpdE enzymes detoxified the pesticides contaminated kimchi composition like Chinese cabbages during fermentation. Furthermore, the OpdA and OpdE enzymes augmented the diversity of new LAB-opd enzymes group in nature.

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