一株水解大豆蛋白细菌的鉴定及其酶学性质研究

Identification and enzymatic properties of a bacterium strain with hydrolyzing soy protein

从我国传统发酵腐乳中筛选出一株对大豆蛋白具有良好水解特性的细菌菌株F1，通过形态学特征和16SrDNA序列分析鉴定该菌株为肉葡萄球菌（Staphylococcuscarmosus）。通过SDS—PAGE泳测得蛋白酶的分子量大约为45ku。在此基础上对该菌的粗酶进行了酶学性质研究，粗酶的最适反应温度和pH值分别为40℃和10．0，在20℃～50℃和pH7．O～11．0范围内具有良好的稳定性。Ca2＋、Mg2＋、K＋、Fe3＋和Zn2＋对粗酶的催化活性有增强作用。粗酶对较高浓度的NaCl和乙醇表现出良好的稳定性。研究结果表明该酶在酶法促熟大豆发酵食品领域有潜在的应用。

A bacterium （F1） with hydrolyzing soy protein was selected from traditional fermented soybean food. The strain was identified as Staphylo- coccus camosus based on the 16S rDNA sequences. The molecular mass of the protease was estimated to be 45ku by SDS-PAGE. The protease ex- hibited maximal activity at pH 10.0 and 40℃. The protease was stable at pH 7.0-11.0 and 20℃-50℃. The activity of the protease was enhanced by Ca2＋, Mg2＋, K＋, Fe2＋ and Zn2＋ ions. It was also found that it has a high stability in the presence of NaC1 and ethanol. The results indicated that the protease from Staphylococcus camosus is a good candidate enzyme for potential application in the acceleration of fermented soybean food ripen- ing.