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以蝉蜕、蝇蛆壳两种培养基培养球孢白僵菌不同世代菌株 ,分析其类枯草杆菌蛋白酶(Pr1)和总胞外蛋白酶的产生水平及其与菌株毒力的相关性。结果表明 ,菌株的 Pr1产生水平达到最高的时间较总胞外蛋白酶早 1～ 2天。在蝉蜕培养基中 ,菌株 Pr1产生水平较高 ,而总胞外蛋白酶产生水平大大低于蝇蛆壳培养基中的产生水平。随着世代数的增加 ,Pr1和总胞外蛋白酶产生水平及对家蚕的毒力都明显下降。不同世代菌株在蝉蜕和蝇蛆壳培养基上的 Pr1产生水平与其毒力的相关系数分别为 0 .92和 0 .89,高于总胞外蛋白酶与其毒力的相关系数(0 .84和 0 .6 7)。因此认为在总胞外蛋白酶中 ,Pr1是影响菌株主要毒力因子之一 ,其产生水平的下降是菌株毒力退化的主要原因之一
The different generation strains of Beauveria bassiana were cultured in two kinds of culture mediums such as cicadae and maggot shell, and the levels of subtilisin (Pr1) and total extracellular proteases and their correlation with the virulence of strains were analyzed. The results showed that the strain reached the highest Pr1 production time than the total extracellular protease 1-2 days. In the cicadae culture medium, the strain Pr1 produced a higher level of production while the total extracellular protease production level was significantly lower than that in the fly maggot shell culture medium. With the increase of generation number, Pr1 and total extracellular protease production levels and the virulence of silkworms were significantly decreased. The correlation coefficients of Pr1 production levels and virulences in different generations of strains in C. sinensis and fly maggot shell media were 0.92 and 0.89, respectively, which were higher than those of total extracellular proteases and virulence (0.84 and 0 .6 7). Therefore, it is considered that among the total extracellular proteases, Pr1 is one of the main virulence factors that affect the strain, and the decrease of the production level is one of the major causes of the virulence degradation of the strain