耐酸耐胆盐益生乳酸菌的筛选与鉴定

为了筛选出人源性的耐酸、耐胆盐的益生菌,利用含胆盐(0.2%)的5种选择性培养基(TPY、BHI、MRS、SL、乳酸杆菌选择性琼脂培养基),以溴甲酚紫为酸性指示剂,从婴儿粪便中初步筛选出42株耐胆盐的乳酸菌。根据菌株在pH5.0,4.0,3.5的MRS液体培养基中培养时OD值的变化情况,筛选出3株具有较好酸耐受性的菌株。然后通过平板菌落计数方法测定筛选出的3株菌在pH 3.0条件下0~3h存活率的变化情况,筛选出对酸和胆盐耐受能力最强且最稳定的菌株经16SrDNA分子生物学鉴定为Lactobacillus plantarum。该菌能够作为潜在的益生菌菌株用于后期深入地挖掘其益生功能。

Screening and identification of Lactic Acid Bacteria with acid and bile tolerance

In order to screen human probiotics with the acid and bile resistant abilities, infant stool diluents were spread on five different selective ager plates including TPY, BHI, MRS and SL in this study. 42 strains of lactic acid bacteria with certain bile-tolerance were isolated by selective ager media for lactobacilli, supplemented with bile salt (0.2%) and bromcresol purple as an acid indicator. 3 strains of lactic acid bacteria with high acid tolerance were further selected from 42 strainsaccording to biomass of their cultured in the MRS liquid medium with pH 5.0, pH 4.0 and pH 3.5 respectively. Then the viability of these 3 strains in MRS medium with pH 3.0 was measured by plate colony count technique, resulting in one of them with the highest acid- and bile salt-tolerance. Then this strain was subsequently identified using 16S rRNA-based molecular biological approaches. The strain was molecularly identified to be. Lactobacillus plantarum. The strain could be used as a potential probiotic strain for late digging its probiotic function.