Netter, U.; Bisht, V.; Gaurav, A.; Sharma, R.; Ghosh, A.; Bisht, V. S.; Ambatipudi, K.; Tahlan, K.; Navani, N. K.

The gut microbiome harbors enzymes that can transform dietary cholesterol. Understanding this interaction can help tailor the diet to modulate host lipid homeostasis. Despite being exploited commercially as a probiotic, including a role in cholesterol reduction, the molecular mechanism of cholesterol transformation by lactobacilli still needs to be discovered. Herein, we elucidate the role of a novel microbial 3{beta}-OH-{Delta}5-6-cholesterol-5{beta}-reductase from Limosilactobacillus fermentum NKN51, which directly converts cholesterol to coprostanol. Protein engineering provides insights into the catalytic mechanism of 5{beta}ChR. Phylogenetic studies indicate an abundance of 5{beta}ChR in gut commensal lactobacilli, which shares a common ancestor with plant 5{beta} reductases. Meta-analysis of healthy participants microbiomes highlights the significance of the 5{beta}ChR homologs, and shotgun data analysis establishes an association between higher 5{beta}ChR abundance in diabetic patients (p-0.0213). The discovery and elucidation of the role of lactobacillus 5{beta}ChR in cholesterol metabolism may lead to designing functional foods tailored to ameliorate dyslipidemia.