蜜蜂球囊菌几种胞外蛋白酶的特性

 【目的】研究由蜜蜂球囊菌引起的真菌性疾病白垩病的侵染机制,以及蜜蜂球囊菌胞外蛋白酶的种类及其特性。【方法】利用人工合成的培养基,在体外诱导蜜蜂球囊菌分泌胞外蛋白酶,用硫酸铵沉淀和透析,获得初酶液,利用相应的底物对酪蛋白酶、偶氮酪蛋白酶、胶原蛋白酶、弹性蛋白酶和胰蛋白酶的活力进行测定。【结果】蜜蜂球囊菌分泌的胞外酶主要有酪蛋白酶、偶氮酪蛋白酶、胶原蛋白酶3种,无弹性蛋白酶和胰蛋白酶。对这3种酶的最适温度、pH值以及热稳定性和酸碱稳定性进行了测定。这3种胞外酶的最适反应温度都在40℃左右,最适pH为7左右,均不耐高温,热稳定性差,在中性的pH环境下比较稳定。【结论】蜜蜂球囊菌可以分泌多种胞外蛋白酶,它们的最适pH和温度与蜜蜂消化道内的环境一致。

Characteristics of Ascospheare apis Extracellular Proteinase

【Objcetive】 The objective of the study is to research the extracellular proteinase of Ascospheare apis which plays a key role for the pathogen to infect honeybee. 【Mehtod】 The extracellular enzyme of A. apis was induced, purified and concentrated from an artificial medium. Then different substrates were used to determine the activity of caseinase,azocaseinase,collagenase and elastase trypsin. 【Result】 The results showed that caseinase, azocaseinase and collagenase were secreted by A. apis. Moreover, the optimum reaction temperature of three extracellular pretenase was all around 40℃, the optimum pH was all around 7. They were stable in middle pH buffer system under low temperature but quickly lost their activity under high temperature. 【Conclusion】 Multiple extracellular proteinase could be secreted by A. apis. Their optimum temprature was around 40℃ and the optimum pH was around 7, which was coincident with the physiological parameter of bee larvae midgut.