蒙古族儿童源益生特性双歧杆菌的筛选及鉴定

【目的】双歧杆菌在人和动物胃肠道中发挥着重要的生理作用，然而双歧杆菌能否耐受胃酸、肠液及胆汁酸是影响活菌制剂益生效果的关键因素，本研究旨在从蒙古族儿童粪便中分离筛选出具有良好益生特性的双岐杆菌。【方法】本文采用双岐杆菌选择性培养基对样品进行分离纯化，并对菌株进行生理生化鉴定，以耐受人工胃肠液、耐受牛胆盐为手段对各菌株的益生特性进行评价，并且对B. animalisV9进行了16S rDNA分子生物学鉴定。【结果】本文从12位健康蒙古族儿童粪便中分离得到11株双歧杆菌，经传统生理生化试验鉴定为5株B. adolescentis：A1、H3、G4、A8、V10；3株B. longum：C6、C7、D11；1株B. pseudocatenlatum：B2；1株B. bifidum：G5；1株B. animalis：V9。B. animalis V9具有较强的耐酸性，在pH2.0的人工胃液中厌氧培养3h后存活率为92.4%，而其它10株双歧杆菌在此条件下的存活率均小于31.25%；B. animalis V9在pH2.0的人工胃液中厌氧培养3h后接入pH8.0的人工肠液中消化8h，存活率为99.7%，并且可以耐受0.3%的牛胆盐。进一步对V9菌株进行16S rDNA分子生物学鉴定，发现与Bifidobacterium animalis subsp. lactic BB12的同源性为99%。【结论】本研究结果显示B. animalis V9来源安全，并且具有良好耐酸、耐胆盐益生特性，有望在乳制品及保健类产品中得到广泛的应用。

Screening and identification of probiotic bifidobacterium from Mongolian children

Objective] Bifidobacterium has important physiological activity in gastrointestinal tract of human and animals, and the tolerability of acid, intestinal juice and oxgall bile salt are the key factors that influence the function of living bacteria preparation. In this study, feces of 12 healthy Mongolian children were selected to isolate Bifidobacterium with probiotic properties. Methods] Bifidobacterium was isolated from feces by selective medium and identified by physiological biochemical test. The tolerability of acid, intestinal juice and oxgall bile salt of 11 Bifidobacteria were studied and B. animalis V9 was identified further by molecular biological approach 16S rDNA. Results] Eleven Bifidobacteria isolated from feces of 12 healthy Mongolian children were identified as B. adolescentis (A1, H3, G4, A8 and V10), B. longum (C6, C7 and D11), B. pseudocatenlatum (B2), B. bifidum (G5), B. animalis (V9). B. animalis V9 had the best acid tolerance with the survival rate 92.4% in artificial gastric juice at pH2.0 for 3h, whereas others had lower than 31.25%. B. animalis V9 also had good survival rate (99.7%) in artificial intestinal juice at pH8.0 for 8h after anaerobic cultured 3h in artificial gastric juice at pH2.0, and tolerated oxgall bile salt at concentration of 0.3%. B. animalis V9 was identified further by molecular biological approach 16S rDNA and result showed the homologies of B. animalis V9 was 99% with Bifidobacterium animalis subsp. lactic BB12. Conclusion] B. animalis V9 had good probiotic properties to be potentiallyused in dairy products and health products.