| One Pseudomonas diminuta strain M5R14 was selected as object in the present study,which was isolated from the tame sludge in water course of Pesticide Factory of Hangzhou and could degrade a variety of strains of synthetic pyrethroid insecticides.The inner and extra-cell crude enzyme of Pseudomonas diminuta strain M5R14 prepared by ultrasonic break up and centrifugal separation methods,and the characteristics of crude pyrethroid pesticide-degrading enzyme were primary studied.The results showed that pyrethroid pesticides degrading enzyme excreted from the strain of was intracellular enzyme,the best pH for bifenthrin,fenpropathrin and cypermethrin degradation was 6.5,as well as the most appropriate temperature was 35℃.Besides,the Michaelis constant and maximum degradation rate varied due to pyrethroid species.The Michaelis constant to such 3 pyrethroid pesticides were 4162.73,1092.57,1171.97 μmol/L respectively,and the maximum degradation rate to such 3 pyrethroid pesticides were 0.152,0.038,0.043 μmol/(min·mg) protein.The degradation process of crude degrading enzymes to such 3 pyrethroid pesticides was fitted for first-order kinetic equation and the half life (t1/2) were 119.51,113.63,108.30 min,respectively.Crude degrading enzymes for the three pyrethroid insecticides could be maintained high degradation activity when the pH ranging from 5.0 to 8.0,and the temperature was 20℃ to 50℃,indicating the degrading enzymes were with large scope of pH stability and thermalstability.Therefore,there's higher potential in controlling the residuals of synthetic pyrethroid insecticides. |
