羊源芽孢益生菌的筛选与Y5-39菌株的鉴定及其耐受性试验

Screening and Identification of the Probiotics Strain Y5-39 Showing Antidysenteriae Effects from Sheep

为了筛选对羔羊腹泻有治疗作用的益生菌。采用琼脂平板扩散法,以大肠杆菌(Eacterium coli)菌株为病源指示菌,从健康小尾寒羊的新鲜粪便中分离得到一株具有较强抑菌活性的拮抗细菌Y5-39菌株。对该菌株进行形态特征的观察和生理生化试验,结合16S rDNA序列分析,并与相应种、属的菌株进行对比,表明Y5-39与芽孢杆菌Bacillus相应性状相近。用BLAST软件在Genbank数据库中对Y5-39菌株的序列进行比对,经分析Y5-39菌株与地衣芽孢杆菌(Bacillus licheniformis)的相似性水平达到99.92%,且二者在所构建的系统发育树上处于同一个分支。最终鉴定Y5-39菌株为地衣芽孢杆菌。通过测定菌株Y5-39在人工胃液、不同pH值和不同浓度胆盐环境中的存活率,结果表明,此菌株对酸性环境、人工胃液和胆盐有很强的耐受力。

The research was to screening the probiotics curing diarrhea of lamb. A strain Y5-39 which had strong inhibition capability against Eacterium coli was obtained with the agar plate diffusion method from dung of healthy Han Sheep. Then the strain Y5-39 was characterized by morphological and culture features observation,physiological and biochemical experiments and 16 S rDNA sequence analysis. As the morphology characteristics and physiological and biochemical characteristics of the stain was similar to Bacillus and the similarity of the 16S rDNA sequences between strain Y5-39 and the type strain was up to 99. 92% . According to the results,strain Y5-39 was finally identified as Bacillus licheniformis. The survival rates of bacteria after being inoculated in artificial gastric juice,acid and bile salt environment for different time was determined. The test results showed that Y5-39 showed stronger tolerance in bile salt,artificial gastric juice and acid environment.