健康成人粪便中双歧杆菌的分离鉴定及其发酵乳体内特性研究

为筛选具有潜在益生功能的双歧杆菌，采用MRS培养基，结合菌落形态观察和16S rDNA基因序列同源性分析，从上海地区健康的成人粪便中分离鉴定双歧杆菌，通过7 L发酵罐发酵试验筛选优良菌株，并利用其制备发酵乳，对发酵乳的体内特性进行研究。结果表明，分离并鉴定到3株长双歧杆菌（Bifidobacterium longum）（编号为P-1、P-2和P-3），其中菌株P-2制备的发酵乳在稳定期活菌数最高，遗传稳定性好，被确定为优良菌株，并被命名为DD98。菌株DD98制备的发酵乳能显著增加小鼠胃肠道内有益菌、减少有害菌的表达（P＜0.05），具有调节肠道菌群的作用。此外，能维持小鼠正常的体质量、血常规指数，有利于小鼠脏器的生长。

Isolation and identification of Bifidobacterium from adult faeces and its characteristic of fermented milk in vivo

Bifidobacteria strains with potential probiotic properties were isolated from faeces of healthy adults in Shanghai area by MRS medium and identified by colony morphology observation and 16S rDNA gene sequence homology analysis.The dominate strains were screened by 7 L fermenter fermentation test,and the milk was fermented by the dominant strain and the in vivo characteristic research of the fermented milk was studied.The results showed that 3 strains of Bifidobacterium longum(P-1,P-2,P-3)were isolated and identified.Since the fermented milk fermented by strain P-2 with good genetic stability had the highest viable counts in the stable phase,the strain P-2 was identified as the dominate strain and named DD98.The fermented milk had the function of regulating intestinal bacteria,which could significantly increase the expression of beneficial bacteria and reduce harmful bacteria in the gastrointestinal tract of mice(P<0.05).In addition,the fermented milk could maintain the normal body mass and blood routine index of mice,which was beneficial to the growth of mice organs.