降解菌djl-6多菌灵水解酶的提取及性质

以往对多菌灵降解菌Rhodococcus qingshengii sp.nov.djl-6的降解途径研究显示,该菌株首先通过多菌灵水解酶将多菌灵水解成二氨基苯并咪唑,从而对多菌灵进行脱毒.为开发酶制剂并有效应用于环境中残留污染物多菌灵的降解,比较了不同提取方法(高压细胞破碎、超声波破碎和添加溶菌酶破碎)对多菌灵水解酶提取效率的影响,并对其酶学特性进行了初步研究.结果表明,djl-6菌株在LB培养基中培养72~84 h,生长量和产酶量均达到最大值.采用超声波破碎提取酶的效率较高(蛋白浓度为7.92 mg/mL),但酶活损失较大(比酶活只有1.2 U/μg protein).多菌灵水解酶属于一种胞内组成型酶.该酶水解多菌灵的最适pH值为7.0,最适温度为30℃,Zn2+和K+对酶活有一定的抑制作用.

Extraction and Characters of Carbendazim Hydrolase from Strain djl-6

Rhodococcus qingshengii sp.nov.djl-6 is a strain of carbendazim-degrading bacterium.The previous studies on the metabolism pathway revealed that it could hydrolyze carbendazim to 2-aminobenzimidazole by carbendazim hydrolase,resulting in the detoxification of carbendazim.For developing the enzyme application in degradation of carbendazim,in the present study,the characteristics of crude carbendazim hydrolase extracted from strain djl-6 by different methods(French pressure,ultrasonic method,and lysozyme addition) were investigated.The results showed that after cultured in LB medium for 72~84 h,the growth and enzyme yield of strain djl-6 achieved the highest values.The extraction by ultrasonic method could obtain more enzyme yield(7.92 mg/mL of protein concentration) but lower enzyme activity(only 1.2 U/μg protein of relative enzyme activity).The carbendazim hydrolase was a constitutive enzyme,mainly located in cell.The optimum pH value and temperature for the carbendazim hydrolyzing activity of this enzyme was 7.0 and 37 ℃,respectively.Besides,Zn2+ and K+could inhibit the enzyme activity to some degree.