Characterisation of Lactobacillus fermentum SM-7 isolated from koumiss, a potential probiotic bacterium with cholesterol-lowering effects

Abstract

Lactic acid bacteria (LAB) have been demonstrated to have cholesterol-reducing effects in many studies. Lactobacillus fermentum SM-7 screened from ten LAB strains isolated from koumiss, a fermented milk drink, reduced cholesterol by 66.8%. It also showed acid and bile tolerance as well as antimicrobial activity against pathogenic Escherchia coli and Staphylococcus aureus. Lactobacillus fermentum SM-7 cells assimilated 61.5% and co-precipitated and absorbed 38.5% of the cholesterol in the media. Co-precipitation of cholesterol with cholic acid increased rapidly at pH levels below 6. In vivo experiments using L. fermentum SM-7 on artificially induced hyperlipidaemial ICR mice significantly decreased serum total cholesterol and total triglyceride levels, low-density lipoprotein cholesterol concentrations and atherogenic index (P < 0.01), while serum high-density lipoprotein cholesterol concentrations did not increase significantly (P > 0.05). The body weight and liver weight/body weight ratio of SM-7 groups were lower than those of mice on a high-cholesterol diet that were not given lactobacilli. There was no bacterial translocation in the liver, spleen or kidney of experimental mice. The results suggested that L. fermentum SM-7 is a potential probiotic bacterium with cholesterol-lowering effects.