不同菌种发酵对辣木叶蛋白降解的影响

以辣木叶粉为原料，研究自然发酵和7株不同菌株接种发酵过程中理化指标（pH、总酸、蛋白酶活力、蛋白含量、氨基酸态氮含量）的变化规律，并采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）筛选降解辣木叶蛋白的优良菌株。结果表明，发酵过程中pH值随发酵时间延长而降低，总酸含量逐渐上升，蛋白酶活力呈先上升后下降趋势。7株不同菌株中，纳豆芽孢杆菌（Bacillus natto）和棉籽糖乳球菌（Lactococcus raffinolactis）发酵的辣木叶粉在24 h时蛋白酶活力最高，分别为270.58 U/mL和248.34 U/mL，发酵结束时，蛋白含量分别下降20.24 mg/g、21.95 mg/g，氨基酸态氮含量明显高于其他组。SDS-PAGE结果显示，纳豆芽孢杆菌和棉籽糖乳球菌能够降解分子质量70 kDa和35 kDa的两种主要蛋白。因此该研究选出纳豆芽孢杆菌和棉籽糖乳球菌作为发酵降解辣木蛋白的优良菌株。

Effects of different strains fermentation on the degradation of Moringa oleifera leaf protein

Using Moringa oleifera leaves powder as raw material, the changes of physicochemical indicators (pH, total acid, protease activity, protein content, amino nitrogen) during natural fermentation and fermentation processes by 7 different strains were studied, and the superior strain with M. oleifera leaf protein degrading ability was screened by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The results showed that the pH decreased with the extension of the fermentation time, the total acid gradually increased, and the protease activity showed a trend of first increasing and then decreasing during the fermentation process. M. oleifera leaf powder fermented by Bacillus natto and Lactococcus raffinolactis among the 7 strains had the highest protease activity at 24 h, which were 270.58 U/ml and 248.34 U/ml, respectively. At the end of fermentation, the protein content decreased to 20.24 mg/g and 21.95 mg/g, respectively, and the amino nitrogen content was significantly higher than other groups. SDS-PAGE results showed that B. natto and L. raffinolactis could degrade the two main proteins with molecular weight of 70 kDa and 35 kDa. Therefore, B. natto and L. raffinolactis were selected as the superior strains for M. oleifera degradation.