禽类饲用芽孢杆菌的筛选及固体发酵条件优化

Selecting of Fowls'Feed Bacillus spp.and Optimizing Conditions of Solid State Fermentation

筛选得到3株适用作为禽类饲料添加剂的枯草芽孢杆菌,分别命名为B395、B605和BM1。该3株菌株均能够在42℃正常生长,能抑制大肠杆菌、金黄色葡萄球菌,且能耐受0.3%胆盐,能产生淀粉酶、蛋白酶、纤维素酶。通过饲喂试验,观察到菌剂组可明显促进肉鸡生长,有效降低料肉比。选取B395作为试验菌株,以培养后活菌数为指标,得到其最佳固体发酵条件为麦麸∶稻糠为3∶2、葡萄糖0.5%、尿素2%、KH2PO40.5%,含水量45%、接种量5%、温度37℃、培养时间3d。按上述培养条件,对B395进行培养,摇瓶式发酵可使活菌数可达到(1.3±0.1)×1010CFU/g,浅盘式发酵可使活菌数达到(1.3-1.4)×1010CFU/g;并对B605和BM1进行培养,得到活菌数均超过109CFU/g。

Three strains of Bacillus subtilis B395,B605 and BM1,with the ability to grow up at 42℃normally,to inhibit Escherichia coli and Staphylococcus aureus,to tolerate bile of 0.3%,and produce amylase,protease and cellulose,which were selected for the fowls＇feed additives.In the experimental test,the probiotics could significantly promote the growth of chickens and increase the ratio of feed conversion.B395 was chosen as tested strain,and its optimal solid state fermentation conditions were wheat bran：rice chaff 3：2,glucose 0.5%,urea 2%,KH 2 PO40.5%,water content 45%,inoculum concentration 5%,37℃and 3 d by taking the living bacteria amount as the index.In the optimal conditions,the number of B395 was（1.3±0.1）×1010 CFU/g in flask fermentation and（1.3-1.4）×1010CFU/g in platter fermentation.The numbers of B605 and BM1 would exceed 109CFU/g under the conditions mentioned above.