陕西省榆林市一株仔猪肠道乳杆菌的筛选鉴定与安全性评价

Screening,Identification and Safety Evaluation of One Strain of Lactobacilli Isolated from Piglet Intestinal in Yulin City of Shaanxi Province

为寻找经济、安全、有效的益生菌类饲料添加剂,从陕西省榆林市健康断奶仔猪肠道中分离筛选出1株乳杆菌,通过细菌形态学观察、生理生化试验以及16S rRNA基因同源性分析对该菌株进行鉴定,并进行了耐酸、耐胆碱盐试验以及动物安全性试验。结果显示:该菌株的形态特征与生化试验结果均符合乳杆菌的典型特征,其16S rRNA基因序列与罗伊氏乳杆菌(Lactobacillus reuteri)具有极高的同源性,相似度超过99%;结合生化试验结果,将该菌株鉴定为罗伊氏乳杆菌,并命名为YL006。该菌株在pH 2.0和0.2%胆盐质量分数条件下表现出显著的耐受能力;动物试验中,所有试验小鼠均存活且生长状况良好,日采食量和日增重较对照组有所增加。结果表明,分离筛选出的罗伊氏乳杆菌YL006在耐酸、耐胆盐以及生长状态、安全性方面表现优异,对小鼠生长具有一定的促进作用,具有用作益生菌饲料添加剂的应用潜力。

In order to search for economical,safe and effective probiotic feed additives,one strain of Lactobacillus was isolated and screened from intestines of healthy weaned piglets in Yulin City of Shaanxi Province,and identified through bacterial morphology observation,physiological and biochemical test and 16S rRNA gene homology analysis,followed by acid and choline salt resistance test as well as animal challenge test.The results showed that the isolate had the morphological and biochemical characteristics consistent with typical characteristics of Lactobacillus,and its 16S rRNA gene sequence was highly identical to Lactobacillus reuteri,with a similarity of above 99%;and the isolate was identified as Lactobacillus reuteri and named as YL006 based on the results of biochemical test.YL006 strain represented significant tolerance at pH 2.0 and bile salt with mass fraction of 0.2%;and all tested mice survived and grew well,with an increase in daily feed intake and weight gain compared to the control group.In conclusion,the isolated YL006 strain was excellent in acid and bile salt tolerance as well as growth status and safety,contributing to the growth of mice to a certain extent,with a potential to be used as a probiotic feed additive.