The Colonization Of Lactobacillus In Intestinal Tract And Adjustment To Intestinal Flora

It is clarified that the probiotic which have a positive influence on the metabolic activity of the intestinal flora, must colonize the Intestinal tract before they exert the beneficial effects. Lactobacillus casei LC2W,Lactobacillus plantarum ST-Ⅲand Lactobacillus casei BD-Ⅱwhich have different benefits, were scanned by Technical Center of Bright Dairy. In this paper a lactobacillus with the best bio-characters was chosen, and its colonization In Intestinal tract and its effect on the intestinal flora were investigated.By comparing the grow char acters and the ability for long-term survival in simulate human gastrointestinal tract the lactobacillus with the best bio-characters was chosen. Results showed that Lactobacillus plantarum ST-Ⅲ's bio-characters were better than other ones. After anaerobically incubated in MRS Broth at 37℃, 16h, the amount of ST-Ⅲwas more than 109cfu/ml, after the cultures stored at 4℃for 28 d, the amount of bacteria still not less than 90%. It could survival and grew in MRS Broth with 7.5% (m/m) NaCl or 0.30% bile and exerted antibacterial effect on some pathogenic bacteria. ST-Ⅲ's resistant to simulate human gastrointestinal tract was stronger than any other bacteria, pH2.5's gastric juice and Intestinal juice have little effect on this strain.Two methods, incubation and Denaturing Gradient Gel Electrophoresis, were applied to assess ST-Ⅲ's colonization in intestinal tract of Wistar rats. Results showed that ST-Ⅲmostly colonized rats'colon and ileum, the amount reached separately 107cfu/g and 108cfu/g, only little ST-Ⅲcolonized the jejunum and the caecum, the amount was less than 105cfu/g, but it couldn't colonize the rectum and the duodenum. ST-Ⅲcolonized the colon for about ten days, the ileum for seven days and the caecum for only three days.By incubation the effects of ST-Ⅲon the composition of the intestinal microflora was assessed. Results showed ST-Ⅲcould increase the amount of lactobacillus in feces of rats and decrease the amounts of Clostridium perfringens and Entericbacilli, but had little effect on Enterococcus and Bifidobacterium. Skim milk with 108cfu/ml ST-Ⅲhas improved the balance of intestinal microflora, and the resultful dose was 108cfu/ml, and the adjustment hold about five days after stopping the ingestion.The research showed Lactobacillus plantarum ST-Ⅲhad excellent bio-characters and could resist to the simulate human gastrointestinal tract; ST-Ⅲmostly colonized the colon and the ileum; Skim milk with 108cfu/ml ST-Ⅲcan improve the balance of the intestinal microflora for several days.