不同基质传代白僵菌菌株胞外蛋白酶和几丁质酶产生水平与菌株对桑天牛幼虫毒力的关系

研究了对桑天牛幼虫具有不同致病力的各种传代白僵菌菌株胞外蛋白酶和几丁质酶的产生水平,并分析其与菌株致病力变化的关系。结果表明:不同基质传代菌株随着培养时间的延长,胞外蛋白酶和几丁质酶活性逐渐升高,达到最高值后基本趋于稳定,几丁质酶产生时间要滞后于胞外蛋白酶;通过寄主桑天牛幼虫传代的白僵菌菌株比通过普通查氏培养基传代的菌株具有更强的产酶能力;不同菌株胞外蛋白酶和几丁质酶产生水平与菌株毒力有一定相关性,尤其是产酶高峰值与菌株的LC50呈显著相关性,可将其作为菌株初步筛选的参考性毒力指标。

Relationships Between Extracellular Protease and Chitinase Activity Level of Different Successive Reisolates of Beauveria bassiana and Virulence Against the Apriona germari Larvae

The extracellular protease and chitinase activity level of the different successive reisolates of Beauveria bassiana,which have different pathogenicity to Apriona germari larvae,and its correlation with the pathogenicity changes were investigated in this paper.The results showed that in the test range,extracellular protease and chitinase activity increased with the extension of culture time and stablized at the maximum.But the stage of chitinase production lagged behind that of extracellular protease.Extracellular protease and chitinase activity level of successive reisolates obtained by repeatedly passing through the A.germari larvae was higher than that by repeatedly passing through the Czapek medium.There was some correlation between the extracellular protease and chitinase activity level and the virulence against the A.germari larvae,especially the significant relationship between the maximal activity and the LC50was found.It suggested that extracellular protease and chitinase activity level could be used as an referrence virulence index for selection of candidate isolates.