Studies on the resistance of cholesterol-lowering of lactic acid bacteria to simulated gastrointestinal circumstance in vitro

Acid and bile are primary natural barriers in the gastrointestinal tract, and tolerances of the probiotics help to survive and exert their beneficial effects. Eight lactic acid bacteria strains were selected based on cholesterol-lowering ability from Chinese traditional kefir grain, named lactococcus lactis subsp lactis KS4, J4, P1 and P5, lactobacillus casei KTx, KL1 and J1 and streptococcus thermophilus Tx. The strains were cultured in MRS medium (pH 3.0 and 0.3% bile salt). Acid and bile salt tolerances were evaluated by measuring and comparing optical density values at 600nm (OD600). The o-phthalaldehyde method (OPA) was used. The cholesterol-lowering rate of strains KL1 and J1 are 60.1% and 55.3% to simulated gastrointestinal adverse circumstance in vitro. The results indicate that lactobacillus casei KL1 and J1 are effective as probiotics with cholesterol-lowering activities. © (2013) Trans Tech Publications, Switzerland.