Isolation And Identification Of Lactobacillus From Human Intestine And Study On Their Resistant Ability And Fermentation Characteristics

In this study, Lactobacilli were isolated from feces samples collected from health young people in eight regions such as Tibet, Xinjiang, and Inner Mongolia and so on. The biodiversity of the human intestinal flora in those three minority areas was analyzed statistically. And then, the tolerance of bile salts and acid, and fermentation characteristics of these indentified Lactobacilli strains had been curried out.The biodiversity of Enterococcus, Lactobacillus, Bifidobacterium, C. perfringens isolated form38samples collected form Mongolian, Tibet and Kazakh nationality showed:residences have significant impacts (p<0.05) on the concentrations of microflra, while the gender hve not any sigificant effect. Moreover, dietary protein fat, carbohydrate intake had a sinificant effect on the composition of micro flora in human intestinal.The results showed that13species of Lactobacillus isolated from health young people feces samples include Lactobacillus ruminis, Lactobacillus gasseri, Lactobacillus casei, Lactobacillus vaginalis, Lactobacillus mucosae, Lactobacillus brevis, Lactobacillus helveticus, Lactobacillus crispatus, Lactobacillus acidophilus, Lactobacillus reuteri, Lactobacillus plantarum, Lactobacillus fermentum, Lactobacillus rhamnosus. Generally, Lactobacillus ruminis and Lactobacillus gasseri were the predominant species among all isolates accounting total isolates by53.45%and13.79%.There were some differences in quantity and species of isolates of lactobacillus among the eight regions of China.21strains of Lactobacilli (including5species) were isolated from Tibet,15strains of Lactobacilli (including4species) were isolated from Xinjiang,12strains of Lactobacilli (7species) were isolated from Inner Mongolia. Among them, Lactobacillus ruminus were the predominant species in three regions. However, the species of isolates from Tibet and Xinjiang were single. Moreover, there were a few species and quantity of lactobacillus isolated from the other six regions.Bile salts and acid tolerance and fermentation research had been done concerning9strains of seven species including L. casei, L. brevis, L. helveticus, L. acidophilus, L. reuteri, L. plantarum, L. fermentum. The results showed all the strains grew well in pH3.0. The significant difference (p<0.05) had emerged on the survival rate after11hours digestion in the artificial gastric juice. Especially, L. plantarum from human gut and L. plantarum P8kept high survival rate after digestion. The strains of L. casei, L. brevis, L. acidophilus, L. reuteri, L. plantarum, L. fermentum from human intestinal and control strains all have high tolerance to bile salt and acid. The fermentation characteristics of11strains were tested. The results showed that strains from the feces sample have lower fermentation ability than the control strains. During storage process, the viable count in fermented milk were decreased in all samples, but the count of viable cells were maintained over than1.0×10CFU/mL. especially L. casei Zhang had the best fermentation and storage characteristic. The survial rate of L. casei Zhang was higher than others.