Mechanisms of cholesterol-lowering effects of lactobacilli and bifidobacteria strains as potential probiotics with their bsh gene analysis

Abstract

The bile salt hydrolase (BSH) enzyme activities of human-derived lactic acid bacteria and bifidobacteria were evaluated. The highest enzyme activity was identified as 1.76 ± 0.23 U/mg protein for Bifidobacterium breve A26 and 1.42 ± 0.11 U/mg protein for Lactobacillus plantarum LA3. The bile salt deconjugation ability of the 6 isolates representing the highest BSH enzyme activity was calculated as the release of cholic acid and was between the range of 2.03 ± 0.22 and 1.05 ± 0.25 mM. The strains with high BSH enzyme activity also showed high deconjugation ability (p < 0.01). The effect of increasing bile concentrations on the growth of bacteria and their cholesterol removal abilities based on cholesterol precipitation were determined. Cholesterol removal in control medium was between 22.6 ± 0.4 and 26.5 ± 0.4%. The highest value was recorded at a 0.2% bile concentration. As the biliary concentration increased, a decrease in cholesterol removal and viability of the bacteria was noted in all strains. The percent of similarity of the bsh gene region between different genes was specified. The results may throw some light on proving the ability of these probiotics either as a novel alternative or as adjuvants to chemical drugs in treating hypercholesterolemia.