胞外蛋白酶和脂酶活性作为球孢白僵菌毒力指标的可靠性分析  

RELIABILITY OF EXTRACELLULAR PROTEASE AND LIPASEACTIVITIES OF BEAUVERIA BASSIANA ISOLATES USEDAS THEIR VIRULENCE INDICES

作　　者：冯明光[1] 

机构地区：[1]浙江农业大学生物科学系,杭州310029

出　　处：《微生物学报》1998年第6期461-467,共7页Acta Microbiologica Sinica

基　　金：国家杰出青年科学基金;国家自然科学基金和浙江省自然科学基金

摘　　要：通过测定17株不同来源球孢白僵菌(Beauveria bassiana)的胞外蛋白酶活性(PU,μmol·ml^(-1)·min^(-1))和脂酶活性(LU,μmol·ml^(-1)·h^(-1))及其对血黑蝗(Melanoplussanguinipes)的毒力,分析用酶活性作为毒力指标的可靠性.结果表明,菌株间毒力和酶活性差异较大,LT_(50)的变化范围为5.27~16.89d,PU和LU分别为0.47~3.37×10^(-2)和0.00~56.75.将PU与LU分别对接种后各日累计死亡率及LT_(50)进行回归分析,发现各菌株PU与其毒力相关显著,但LU却与毒力相关不显著.对接种后7d的死亡率,PU可表达其变异的67%,也是最大表达率.因此,PU可作为大量菌株初筛的参考性毒力指标,但应谨慎使用,不能以PU测定完全取代常规的毒力测定.脂酶活性不宜作为所试菌种的毒力参考指标.The extracellular protease and lipase activities of 17 Beauveria bassiana isolates from different hosts and countries were evaluated for the reliability for the indices of their virulence to the migratory grasshopper, Melanoplus sanguinipes. Virulence assay of each isolate included about 30 10-d-old grasshoppers receiving topical inoculation with the suspension of 107 conidia / ml. In the assays of the enzymes, N-succinyl-Ala-Ala-Pro-Phe-p -nitroanilide and p-nitrophenyl palmitate were used as a substrate to measure the activities of protease (3 replicates) and lipase (4 replicates) in the filtrates of gelatin-based and sunflower oil-based liquid cultures of each isolate, respectively. Varying among the isolates assayed, the estimates of LT50's, protease units (PU), and lipase units (LU) were 5.27-16.89 d, 0.47-3.37 × 10-2 μmol · ml-1 · min-1, and 0.00-56.75 μmol · ml-1 · h-1, respectively. Regression analysis revealed that PU was significantly (P<0.01) correlated to the daily cumulative mortality of M. sanguinipes 5-17 d after inoculation and the LT50' s whereas LU had little correlation to either the mortalities or the LT50' s (P>0. 10). Based on the determination coefficients (r2) from the regressions, PU alone interpreted at most 67% of the variation in the mortality 7d after inoculation but less than 50% in most of the days considered and only 38% in LT50's. Thus, the author suggested that PU could be used as virulence index only for early-stage selection of candidate isolates in large quantity and could not entirely replace conventional virulence assay method that remains most reliable.

关 键 词：球孢白僵菌 胞外蛋白酶 脂酶 毒力 血黑蝗 

分 类 号：S482.7[农业科学—农药学] S481.1[农业科学—植物保护]