一株枯草芽孢杆菌的饲料学特性研究

Study on the Feed Performance of a Strain of Bacillus Subtilis

枯草芽孢杆菌（Bacillus Subtilis）具有调节肠道微生态平衡、提高饲料转化率和提高动物免疫力等功能,是微生物饲料添加剂的常用菌种。但由于对选育、传代和保藏等技术的不重视,导致其性能严重退化,选择抗逆性强和发酵效果佳的菌株用于动物饲料添加具有重要意义。该研究观察了一株枯草芽孢杆菌的形态特征,测定了其生长曲线、抗逆性及所发酵饲料的p H值和几种消化酶的活力变化,以为其推广应用提供依据。结果表明：该株枯草芽孢杆菌具有本种所特有的形态特征;在37℃、180 r/min条件下培养,无生长延滞期,生长对数期为0～6 h,生长稳定期为6～10 h,生长衰亡期为10 h以后;分别在37℃、70℃、80℃、90℃和100℃的水浴中处理10 min后,其存活率差异不显著（P〉0.05）;在1%～5%的胆盐中生长存活率均大于100%;在p H值为2的酸性环境中培养60 min,存活率高达58.8%（P≤0.05）;发酵饲料的p H值随发酵时间的延长而明显降低,而蛋白酶、淀粉酶和纤维素酶活力显著升高（P≤0.05）。表明该株枯草芽孢杆菌的饲料学特性优良,是理想的有益微生物饲料添加剂。

Bacillus Subtilis is an ideal probiotic for maintaining and modulation the flora balance of animal intestinal gut, as well improving the feed conversion rate and the production performance of animal. But the performance of Bacillus Subtilis degenerated due to the deficiency of breed and unsuitable transfer of culture. Choosing a strain of Bacillus Subtilis that have a strong resistance and good effect on feed fermentation as animal feed additives are very important.In this study, the morphological characteristic of a strain of Bacillus Subtilis which were donated by a biotechnological company were observed, as well as the growth curves, the re- sistances to high temperature and acid bile were detected by traditional protocol. Furthermore, the pH value and the activity of di- gestive enzyme of the feed fermented by Bacillus Subtilis were investigated in different time point after treatment. The results showed that this strain of Bacillus Subtilis had no obviously lag phase, and its logarithmic growth phase, stationary phase and de- cline phase was 2-6 h, 6-10 h and above 10 h after culture began respectively.No obvious changes in the survive rate were found when pretreated by 37℃, 70℃, 80℃, 90℃ and 100℃ environment for 10 min as well exposed to differential concentration of Bile salts. The survive rate of Bacillus Subtilis attained to 58.8% when treated by a pH of 2 culture buffer for 60 min. The pH value of feed fermented by the Bacillus Subtilis progressively decreased over time, in parallel with activity of protease, amylase and cellulose increased significantly strain of Bacillus subtilis was a feed addition. It was concluded that this valuable probiotic to use in feed addition.