| 49 Lactobacillus strains isolated from 16 samples of traditionally home-made koumiss product in Inner Mongolia - XilinGuole were assessed for potential probiotic properties. After tolerance of all Lactobacilli strains to culture medium at pH3.5 and their survival rates in artificial gastrointestinal juice at pH3.0 had been evaluated, Two stains of Lb.acidophilus ZL12-1 and Lb.caseiZhang were selected.Their Bile resistance and tolerance to imitative gastroenteric environment ,assimilation of cholesterol, deconjugation of sodium taurocholate in vitro and cholesterol –lowering activity of Lb.casei Zhang in vivo were tested. 32 Lactobacillus strains can grow in culture medium at pH3.5. Lb. caseiZhang and Lb. gallinarum ZL12-1 presented high survival rates in artificial gastrointestinal juice at pH3.0 Namely 100% and 57.14% respectively. Lb. gallinarum ZL12-1 can survived in pH 2.0 simulated gastric juices; In pH 3.0 and pH4.0 simulated gastric juices, two strains showed a good tolerance. Espicially, the viabilities of two strains in fermented milk were enhanced extremely in artifical gastrointestinal juice. Bile-tolerant is different between two strains(P<0.05). Lb. caseiZhang presented high resistance to 1.6% bile in medium. Variations between two strains in the ability to deconjugate of sodium taurocholate was not significantly different(P>0.05).Variation between two strains in the ability to decrease cholesterol in vitro was significantly different(P<0.05), The cholesterol assimilated from circumstances by two strains were 49% and 32% respectively. Both viable cells and heat-killed cells of Lb. caseiZhang lowered blood cholesterol concentrition of mice fed with fat-enriched diet, showing the effect on preventing from arteriosclerosis. But the trend of effect was weaked with time. The cholesterol –lowering activity of the strains were mainly due to their bile salt coprecipition activity and the cholesterol assimilation.
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