几株米曲霉成曲胞外蛋白鉴定及发酵结果分析

Identification of Extracellular Protein and Analysis of Fermentation Results of Soy Sauce Koji from Different Aspergillus Oryzae

采用SDS-PAGE电泳和MALDI-TOF-MS技术,鉴定4株米曲霉成曲胞外蛋白表达量最高的4种蛋白,其中2种确定为淀粉酶和碱性蛋白酶,这2种酶在4株米曲霉成曲胞外蛋白中的表达量和都超过胞外蛋白总量的50%,但不同菌株间淀粉酶与碱性蛋白酶表达量比例不同。同时分析蛋白电泳凝胶酶蛋白表达量、酶活与发酵结果的关系,结果表明酶蛋白表达量与酶活力具有较好的一致性。蛋白酶活力低的菌株发酵氨基酸态氮水平并不低,淀粉酶高的菌株发酵生成还原糖较低。

High expressed extracellular proteins of soy sauce koji from four Aspergillus oryzae were separated and identified by SDS-PAGE and MALDI-TOF-MS. The results showed that the expression of amylase and oryzin were about most than about 50% . The ratio of amylase to oryzin was different from different Aspergillus oryzae. The correlation analysis among amylase and oryzin expression, enzyme activity of amylase and neutral protease and fermentation results indicted that expression of amylase and oryzin, enzyme activity were in good agreement,and there was no correlation between the enzyme activity and fermentation results. Amino nitrogen of fermentation by the lower neutral protease stain was not low, and reducing sugar of fermentation by higher amylase stain was not high.