【摘要】 旨在筛选潜在高产纤维素酶的益生菌并探究其益生作用以期用于生产实践。从绵羊肠道内容物中，利用羧甲基纤维素钠(CMC-Na)平板筛选产纤维素酶菌株，测定其纤维素酶活性，筛选出目标菌株；采用形态学分析、生化试验和16S rDNA序列分析对目标菌株进行鉴定；进一步探究其生长曲线、产蛋白酶及α-淀粉酶能力、抑制病原菌能力、耐酸耐胆盐能力、药物敏感性和宿主安全性。结果：从样品中筛选获得8株产纤维素酶菌株，根据透明圈和菌落直径比值以及纤维素酶活性筛选获得产纤维素能力最强的菌株ECL1.2,其羧甲基纤维素酶活性为18.61 U/mL,经鉴定为枯草芽胞杆菌；ECL1.2在培养12 h后进入对数生长期，在培养26 h时进入稳定期；其蛋白酶和α-淀粉酶活力分别为2.08 U/mL和19.7 U/mL;可抑制大肠杆菌、肠炎沙门菌和金黄色葡萄球菌的生长；在pH值为2～7培养4 h及胆盐浓度为0.1%～0.3%培养8 h条件下存活率大于60%,具有一定耐酸耐胆盐性；除对林可霉素低敏、对庆大霉素中敏外，对青霉素、头孢唑啉、克拉霉素、诺氟沙星、万古霉素、利福平极其敏感；对小鼠器官和肠道无危害，并能提高小鼠日增重和采食量。综上，枯草芽胞杆菌ECL1.2可作为潜在益生菌。更多还原

【Abstract】 This study aimed to screen potential high yield cellulase probiotics and to explore its probiotic effect to be used in production practice. Carboxymethyl cellulose plates were used to screen cellulose strains from the intestinal contents of sheep, in order to determine the cellulase activity and to select the target strain. Then, morphological analysis, biochemical tests and sequence analysis of the 16S rDNA gene were used to identify the target strain species. Finally, it’s the growth curve, protease and α-amylase production capacity, pathogen inhibition capacity, acid and bile salt resistance capacity, drug sensitivity, and host safety of the strain. The results showed that eight cellulase-producing strains were selected from the samples. The most cellulose-producing strain ECL1.2 was selected according to the ratio of transparent circle(H) and colony diameter(C) and cellulase activity. The carboxymethylcellulase activity was 18.61 U/mL, which was identified as Bacillus subtilis. ECL1.2 entered the logarithmic growth phase after 16 h of culture and reached a plateau at 24 h of culture. Its protease and α-amylase viability were 2.08 U/mL and 19.7 U/mL, respectively, and it inhibited the growth of Escherichia coli, Salmonella enteritidis and Staphylococcus aureus. Being in pH 2-7 culture for 4 h and in the culture with bile salt at concentration of 0.1%-0.3% culture for 8 h,the strain had a survival rate over than 60%,with a little acid resistance and bile salt resistance. ECL 1. 2 had low sensitivity to lincomycin,intermediate sensitivity to gentamicin,and high sensitive to penicillin,cefazolin,clarithromycin,norfloxacin,vancomycin,and rifampin. It showed safety for mouse organs and intestines,and was helpful for their daily weight gain and food intake. In conclusion,Bacillus subtilis ECL 1. 2 could be used as a potential probiotic fermentation strain.更多还原