乳酸菌对豆粕发酵中特定菌群与多肽水平的影响

Influence on the level of bacteria amount and polypeptides by the lactic acid bacteria in soybean meal fermentation

微生物发酵是改善豆粕营养成分的有效手段,但发酵进程中微生物水平的变化和相关影响尚缺乏足够研究。通过添加外源乳酸菌(屎肠球菌),研究豆粕72h发酵进程内,菌群和蛋白水平的变化情况。结果显示,无论是否添加外源乳酸菌,豆粕中的总菌水平均呈三段式下降。相反,豆粕中的乳酸菌水平成增长趋势,且外源添加对这一趋势具有明显的提速(时间缩短1倍)和增效(1.3倍)作用。在蛋白水平的变化上,上述两组豆粕在粗蛋白和游离氨基酸的时间变化趋势上未有明显差别,但在多肽水平的变化趋势上差别显著。添加乳酸菌组豆粕发酵生成的多肽含量更高,且生成的速度更快(时间缩短1倍),此趋势与豆粕中乳酸菌的增长趋势相对应,表明乳酸菌的添加促进了豆粕中蛋白水解为多肽,但水解不足以产生大量游离氨基酸。

Although fermentation was one of the best ways to improve the nutrition of the soybean meal, the change of the bacteria and their influences On the fermentation process were inadequately clarified. The soybean meal was investigated on the level of the bacteria and the protein during the fermentation in 72 h with/without the addition of the lactic acid （LAB） Enterococcus Faecium. The results showed that the total bacteria account decreased in 3-step Style,no matter whether the LAB was added or not. In contrast, the level of LAB in soybean meal increased during the fermentation,and was strengthened at rate by 100% and at amount by 130% through the addition of extra LAB. With the respect of the protein level,two groups of soybean meal had no significant differences at the changes of crude protein and free amino acid, but were quite different at the changes of polypeptides. The production of the polypeptides in the group with extra LAB were shown to be more efficient at both of the level and rate （by 100%）. These changes of the polypeptides were similar to the LAB changing in two groups, indicating that the production of polypeptides but not the free amino acid was improved by the addition of extra LAB.