Abstract: In this study,effects of different pH,bile salt concentration and simulation human body gastric juice and intestinal tract circumstance on Lactobacillus rhamnosus B from infant intestine were charactered. Under the condition of pH 1.8 maintained for 2 h,the viable count of Lactobacillui rhamnosus strain B reaches more than 107 CFU/ml,and being cultured for 4 h in the MRS-broth(less than 0.5% bile salt),the viable count reach more than 108 CFU/ml,and it increases as time prolonging. The results of simulated gastric juice and intestinal juice experiments showed that the strain can multiply in gastric and intestinal circumstance. The Lactobacillus rhamnosus strain B has strong acid and bile salt tolerance ability and grows better in the circumstance of simulation human body intestinal tract. It is favourable strain for lactic acid bacteria-fermented food.

Key words: Lactobacillus rhamnosus, acid tolerance, bile salt tolerance