缺陷假单胞菌M5R14粗酶液降解拟除虫菊酯类农药特性初探

Primary Study on the Characteristics of Crude Pyrethroid Pesticide-Degrading Enzyme Extracted from Pseudomonas diminuta Strain M5R14

以分离于杭州农药厂污水排放污泥的1株可降解多种拟除虫菊酯类农药的菌株——缺陷假单胞菌M5R14为对象,采用直接离心分离提取和超声波破碎提取的方法获得菌株M5R14的胞外和胞内粗酶,初步探讨了该菌株粗酶液降解拟除虫菊酯类农药的特性.研究表明该菌株降解拟除虫菊酯类农药的酶为胞内酶,粗酶液对联苯菊酯、甲氰菊酯和氯氰菊酯3种拟除虫菊酯类农药降解的最佳pH为6.5,最适温度为35℃,其米氏常数和最大降解速率依拟除虫菊酯类农药品种而不同,对3种拟除虫菊酯类农药的米氏常数分别为4 162.73、1 092.57和1 171.97μmol/L,最大反应速率(以蛋白计)分别为0.152、0.038和0.043μmol/(min.mg).降解粗酶对3种拟除虫菊酯类农药的降解过程满足一级动力学方程模型,降解半衰期(t1/2)分别为119.51、113.63和108.30 min.在pH 5.0～8.0,温度为20～50℃条件下,降解粗酶对所用3种拟除虫菊酯类农药都能保持较高的降解活性,表明降解粗酶具有较宽pH适应范围和较好的热稳定性,在控制拟除虫菊酯类农药残留方面具有较好的应用潜力.

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 4 162.73,1 092.57,1 171.97 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.