继代移殖对球孢白僵菌蛋白酶、几丁质酶、脂肪酶活性的影响及与毒力的相关性

Effects of passage on the activities of protease,chitinase and lipase and their relationships with toxicity in Beauveria bassiana

为探讨继代移殖对球孢白僵菌蛋白酶、几丁质酶、脂肪酶活性的影响及与毒力的相关性,以筛选得到的高毒力菌株B5、BXS与低毒力菌株B11、BZ为出发菌株,通过连续接种松墨天牛幼虫获得H1、H2、H3、H4继代移殖菌株,而连续在PPDA培养基上转接,获得R1、R2、R3和R4继代移殖菌株。分别对各原始菌株与继代移殖菌株进行蛋白酶、几丁质酶、脂肪酶活性与毒力测定,并将每种酶活性与相应菌株对松墨天牛的半致死时间(LT50)作相关性分析。结果表明:高毒力菌株B5、BXS与低毒力菌株B11、BZ在PPDA培养基上继代移殖,随着各菌株对松墨天牛的毒力逐代下降,其蛋白酶、几丁质酶、脂肪酶活性也逐代降低;来源于松墨天牛的B5、BXS、B11菌株通过松墨天牛幼虫继代移殖后随着毒力逐代提高,3种酶活性也逐代上升,但来源于松毛虫的BZ菌株逐代之间3种酶活性差异不显著;相关性分析表明4个原始菌株与继代移殖菌株彼此间的LT50与3种酶活性间均呈极显著的直线负相关。

In order to explore the activities of protease, chitinase and lipase in different passage strains of Beauveria bassiana and their toxicity, we selected two high （Bs, Bxs） and two low toxicity strains （B11, BZ） as the original strains. Then we obtained passage strains of H1 , H2 , H3 and H4 by repeated passages through the larvae of Monochamus alternatus and R1, R2, R3 and R4 passage strains through a PPDA medium. Toxicity and activities of the original protease, chitinase and lipase and those in the passage strains obtained from both methods were measured, and the relationships between the activities of the three enzymes and LTso of the corresponding strains were analyzed. The results show that the activities of protease, chitinase and lipase in the four strains （B5, Bxs, B11 and Bz） all reduced with the gradual decrease in virulence to M. alternatus after being cultured on the PPDA medium. For those reared with M. alternatus larvae, the activities of three kinds of enzymes in B5, BXS and B11, which were isolated from M. alternatus, tended to increase with increasing virulence, while those of BZ, isolated from Dendrolimus, did not show any clear variation between different generations. Analysis of these relations indicated that LT50 was significantly and negatively correlated with the activities of protease, chitinase and lipase in the original and passage strains of B. bassiana.