绿僵菌产海藻糖水解酶培养条件研究

丝状真菌绿僵菌能产生一系列二糖水解酶,其中包括海藻糖水解酶。这些酶在绿僵菌对昆虫的致病过程中起着重要的作用。本文研究了不同碳源、氮源对金龟子绿僵菌Metarhizium anisopliae var. acridum菌株CQMa102产生与分解昆虫血淋巴中海藻糖等二糖相关的海藻糖水解酶活性的影响。结果表明:分别以葡萄糖、麦芽糖、蔗糖、山梨醇和可溶性淀粉为碳源,金龟子绿僵菌均可产生海藻糖水解酶,但最佳碳源是可溶性淀粉,因为由其诱导产生的海藻糖水解酶具有最高的总活性和比活性以及更多的同工酶,山梨醇次之。硝态氮(NaNO₃)作为唯一氮源时,几乎检测不出海藻糖水解酶活性,而铵态氮((NH₄)₂SO₄)或NaNO₃和有机氮(蛋白胨和酵母浸膏)混合氮源作氮源时,海藻糖水解酶活性都很高。在绿僵菌菌丝提取液和滤液的海藻糖水解酶活性比较中发现:CQMa102在多数碳源的培养基中产生的海藻糖水解酶主要分泌到培养基中,仅有少数结合在细胞壁上。

CULTURE CONDITIONS FOR THE PRODUCTION OF TREHALOSE-HYDROLYSING ENZYMES FROM METARHIZIUM ANISOPLIAE

The filamentous fungus Metarhizium produces several extracellular disaccharide-degrading enzymes, including trehalose-hydrolysing enzymes. These enzymes play an important role in the antagonistic action of Metarhizium against most insects. The effects of different carbon sources and nitrogen sources on the production of trehalose-hydrolysing enzymes from Metarhizium anisopliae var. acridum isolate CQMa102 were compared. The results indicated that CQMa102 could produce trehalose-hydrolysing enzymes in medium using glucose, maltose, sucrose, sorbitol or soluble starch as carbon source, but the best carbon source was soluble starch in terms of trehalose-hydrolysing activity and the number of isozymes produced, followed by sorbitol. Among the nitrogen sources tested, ammonium nitrogen and mixture of NaNO3 and organic nitrogen produced higher trehalose-hydrolysing activity than nitrate nitrogen. Comparison of trehalose-hydrolysing enzyme activity between the extracts of mycelia and the culture filtrate showed that the majority of trehalose-hydrolysing enzymes were secreted into liquid culture, only smaller amount of them were bound on cell wall.