Bile salt hydrolase: The complexity behind its mechanism in relation to lowering-cholesterol lactobacilli probiotics

• Bacterial bile salt enzyme is able to hydrolase bile acids into free bile acids. • Bile salt hydrolase is widespread among gut microbes. • Most of lactobacilli encode bile salt hydrolase experimentally reduce cholesterol. • Lactobacilli probiotics-fortified functional food may prevent hypercholesterolemia. Bile Salt Hydrolase (BSH) is a bacterial enzyme (EC 3.5.1.24) that initiates the crucial deconjugation of bile acids (BAs), a process necessary for their transformation into secondary BAs by gut microbes. Recent advance has delved deeper into BAs, recognizing them as endocrine molecules capable of modulating lipid and sugar metabolism in the host. In this review, we elucidate how this wealth of research has broadened our understanding about the intricate mechanisms between BAs and the gut microbiota beyond BSH, underlying the hypocholesterolemic effects of probiotic lactobacilli. We highlight the expanded range of various species of lactobacilli with proven cholesterol-lowering activity both in vitro and in vivo associated with BSH activity. In addition, a summary of genomic and metagenomic studies investigating bsh genes in both gut microbiota and lactobacilli is provided, to be used as an additional tool for the selection of a potential lactobacilli probiotic.