X-Gal在双歧杆菌分离与活菌计数方面的应用研究

Application and Study of X-Gal in Isolation and Counting Bifidobacterium

利用大多数双歧杆菌具有半乳糖苷酶且活性较高的特性,在NPNL培养基中加入X-Gal(5-溴-4-氯-3-吲哚-β-D-半乳糖苷)作为底物,双歧杆菌水解底物释放出吲哚,产生颜色反应。双歧杆菌菌落呈深蓝色,乳酸菌和其它细菌一般为白色或淡蓝色。将X-Gal应用于不同样品中双歧杆菌分离和活菌计数进行对比。这种方法能比较准确的反映双歧制品和婴儿粪便中双歧杆菌的数量,并且大大减少了分离鉴别双歧杆菌的工作量。

Majority of Bifidobacterium have Tilactase and upper enzyme activity, so add X-Gal in the improved NPNL medium as the substrate, Bifidobacterium hydrolysis substrate and release indole, which induces colorresponse. Bifidobacterium colony show dark blue , and other Bacteria generally show white or light blue. X-Gal is used to compare isolation and the count of bifidobacterium in two samples. This method can exactly indicate the count of bifidobacteria in products and babies’ feces. Also it can reduce workloads of bifidobacterium’ isolation and identification.