白僵菌菌株毒力与Pr1蛋白酶活性相关性研究

摘要

利用专一性短肽底物Suc-Ma-Ma-Pro-Phe-pNA对不同突变体菌株进行Pr1蛋白酶活性测定,同时应用玉米螟3龄幼虫对不同突变体菌株进行毒力测定,求算LT50值.以不同突变体菌株的Pr1蛋白酶比酶活为自变量,菌株毒力LT50值为因变量,进行相关性分析,得到突变体菌株的Pr1蛋白酶比酶活与毒力LT50值的线性回归方程:y=－2.411 6x+ 31.405,r2=0.521 6.由线性回归方程可以得出:不同突变体菌株的Pr1蛋白酶比酶活与菌株毒力LT50值呈负相关趋势,说明菌株的Pr1蛋白酶活性越高,菌株的LT50值就越低,菌株的毒力也就越大.两者相关系数r=－ 0.722 2,在0.05水平上相关显著,因此建议将Pr1蛋白酶的酶活性作为菌株初筛时的一个补充指标,但由于Pr1蛋白酶比酶活与菌株毒力LT50值相关性未达极显著水平,所以不建议将Pr1蛋白酶的酶活性作为菌株初筛时的替代指标.%Specific peptide substrate Suc-Ala-Ala-Pro-Phe-pNA was used for Prl protease activity assay, 3rd instar larvae of the corn borer was used for virulence test and LT50 value. The virulence LT50 values and Prl protease activity of different mutant strains were assayed. Using Prl protease activity of different mutant strains as independent variables, virulence LT50 values as dependent variables, the correlation analysis of the virulence LT50 values and Prl protease activity of different mutant strains was conducted. The linear regression equation about Prl protease activity and virulence LT50 value of different mutant strains was obtained: y = - 2.411 6x + 31.405, r2 = 0.521 6. From the linear regression equation, the Prl protease activity and virulence LT50 value about different mutant strains were proven to be negatively correlated, indicating that the higher strain Prl protease activity was, the lower the strain LT50 value was, and the greater virulence of strains was, but the correlation coefficient ( r = - 0.722 2) was not high. Prl protease enzyme activity can only represent the virulence of strains to certain extent and can not be recommended as an alternative indicator but an additional indicator for strain selection.