生淀粉糖化酶产生菌Aspergillus niger(6#)的分离筛选及其产酶条件

从大曲中分离到了1株降解生淀粉能力较强的黑曲霉Aspergillusniger(6#).固体发酵酶活可达2461U/g,RDA值为21.47%;液体发酵酶活可达353U/mL,RDA值为20.30%.以6#菌为实验材料,进一步考察了氮源、碳源及pH对生淀粉糖化酶形成的影响.实验结果表明,无机氮源NaNO3较有机氮源蛋白胨更有利于生淀粉糖化酶的形成;pH是影响生淀粉糖化酶形成的重要因素,低pH会阻遏生淀粉糖化酶的形成;玉米粉和麦芽糖较其它碳源更有利于生淀粉糖化酶的形成.图4表2参12

Isolation of RSGA-producing Strain Aspergillus niger (6#) and Its Enzyme Producing Conditions

A strain, exhibiting strong raw starch-digesting glucoamylase (RSGA) activity, was isolated from Daqu and identified as Aspergillus niger (6#) strain. Its RSGA activities in solid state fermentation and liquid fermentation were 2 461 U/g and 3 53 U/mL, and the RDA values were 21.47% and 20.30%, respectively. The effects of various nitrogen sources, carbon sources and pH on the synthesis of RSGA by 6# strain were studied. The result showed that NaNO_ 3 was better than peptone used as nitrogen source for RSGA production, as the RDA value was higher; pH value was an important factor for RSGA synthesis, and the synthesis of RSGA was depressed at low pH. It was also found that corn flour and maltose were more effective than other carbohydrates in production of RSGA. Fig 4, Tab 2, Ref 12