Title : Probiotics strains of Bifidobacterium bifidum and Lactobacillus for cholesterol removal is related to bile salt hydrolase activity
Abstract:
To determine the validity of the hypothesis of assimilation and/or precipitation of cholesterol three different strains of Bifidobacterium bifidum (B. bifidum) NRRL 1976,1917, KCCM 12096 and their co-culturing were undertaken in TPY medium containing oxgall or taurocholic acid. In the present of taurocholic acid containing medium cholesterol uptake was 10% higher as compare to Oxgall containing medium in mix-culture after 24 and 32h. In the presence of taurocholic acid, the removal of cholesterol was due to precipitation together with un-conjugated bile acids, which was linked to the bile salt hydrolase’s activity of the cells. All cultures deconjugated 60 to 80% of the bile salts. Co-culturing of B. bifidum only demonstrate the differences in the amount of bile salts deconjugation and cholesterol reduction. Cholesterol precipitation occurred at acidification conditions, whereas in pH-controlled cultures, no co-precipitation was observed, it appeared that co precipitation of cholesterol during culturing was a result of formation of deconjugated bile salts. Nevertheless, the behavior was different according to the kind of bile salt as well as strain ability. Small amount of cholesterol was found inside the cells indicating that assimilation phenomena exist but on a very lower level.
Strains of Bifidobacterium bifidum NRRL 1976,1917, KCCM 12096 and Lactobacillus acidophilus NRRL 4495, 4240, Lactobacillus lactis NRRL 1821, 634, Lactobacillus reuterei NRRL14171, Lactobacillus delbruckii NRRL 548, DSM 20081, were compared for their ability to deconjugate bile salts and remove cholesterol from TYP and MRS broths at pH 6.5 and without pH control during growth. Samples grown without pH control dropped to pH 4.01 to 4.2 during 24 h of incubation, depending on the culture. However, mixed culture of three strains of B. bifidum 1976,1917 and 12096 and L. acidophilus NRRL 4240 differed significantly in the amount of cholesterol removed during growth with or without pH control. Mixed culture of seven strains of Lactobacilli removed very little amount of cholesterol from the broth.
