Biodegradation of Cholesterol by Cellulosimicrobium cellulans YS01 Isolated from the Gut of Healthy Individuals

An excessively high serum cholesterol (CHOL) level in humans can easily lead to cardiovascular diseases (CVDs), including hypertension and coronary heart disease. In this study, a CHOL-lowering bacterium, <i>Cellulosimicrobium cellulans</i> YS01, was isolated from healthy human intestinal microbiota and identified via average nucleotide identity (ANI) analysis. The cells of YS01 degraded 74.00% of CHOL within 5 d, which decreased from the initial 1.00 g/L to 0.26 g/L. And its extracellular crude enzymes achieved equivalent efficiency within 24 h, which decreased from the initial 0.50 g/L to 0.13 g/L. The results indicated that YS01 indeed has a strong ability in the biodegradation of CHOL. Furthermore, the whole genome analysis of YS01 revealed that cholesterol oxidase and choloylglycine hydrolase encoded by gene <i>choD</i> and gene <i>cbh</i>, respectively, may play key roles in the conversion of CHOL. Cholest-4-ene-3-one was produced from CHOL through the catalysis by cholesterol oxidase, and choloylglycine hydrolase was also involved in another biodegradation pathway of CHOL. The results provide scientific insights into the mechanisms of biodegrading CHOL using <i>C. cellulans</i> YS01 and lay a solid foundation for the development of new CHOL-lowering strategies based on microbial therapy.