The alleviating effect of different bile salt hydrolase gene-encoding Limosilactobacillus fermentum strains on hypercholesterolemia in mice

This work aimed to investigate the impact of different bile salt hydrolase (BSH) distributions on the cholesterol-lowering capacity of Limosilactobacillus fermentum through comparative genomics, molecular docking simulations , and in vitro and in vivo experiments. BSH is considered an important characteristic for probiotics to lower serum total cholesterol (TC). Strains with different BSH distributions possess varying abilities to hydrolyze bile salts. L. fermentum has been demonstrated to exhibit significant cholesterol-lowering potential and may alleviate hypercholesterolemia . In this study, three types of BSHs were identified across 219 strains of L. fermentum , and molecular simulations revealed that BSH3 formed the most stable binding with substrates. Based on the distribution patterns of BSHs, L. fermentum strains were classified into three types: L. fermentum Ⅰ (containing BSH2), L. fermentum Ⅱ (containing BSH1 and BSH2), and L. fermentum Ⅲ (containing BSH1, BSH2, and BSH3). In vitro experiments involving 34 strains of L. fermentum demonstrated notable variations in bile salt hydrolysis and cholesterol-lowering capability across different types, with L. fermentum Ⅲ showing superior performance compared to the other two types. After 12 weeks of a high-cholesterol diet (HCD), C57BL/6 N mice treated with L. fermentum Ⅲ, Ⅱ, and Ⅰ showed serum TC reductions of 27.19 %, 21.65 %, and 25.15 %; low-density lipoprotein cholesterol (LDL-C) reductions of 25.06 %, 8.11 %, and 9.41 %; and increased fecal total bile acids (TBAs) excretion by 10.97 %, 7.24 %, and 6.02 %, respectively. Overall, the alleviating effect of L. fermentum Ⅲ was markedly superior to the other two types. This indicates the important role of BSHs in the alleviation of hypercholesterolemia by L. fermentum , providing a valuable perspective for screening probiotics capable of alleviating hypercholesterolemia .