Screening of an efficient cholesterol-lowering strain of Lactiplantibacillus plantarum 54–1 and investigation of its degradation molecular mechanism

In this study, an efficient cholesterol-lowering strain of Lactiplantibacillus plantarum 54–1 was screened and its degradation molecular mechanism was investigated. Furthermore, a novel practical MRS medium for screening cholesterol-lowering lactic acid bacteria (LAB) was developed based on ultrasound treatment. L. plantarum 54–1 was found to have the highest ability to eliminate cholesterol (340.69 ± 5.87 µg/mL). According to SEM and the count of viable LAB results, the morphology of LAB in the cholesterol-containing medium developed in this experiment was close to the normal (full and smooth), and it can grow normally. Metabolomics revealed that L. plantarum 54–1 initially converted a portion of cholesterol to 7α-hydroxy-cholesterol and then to the key metabolite taurine, via the phosphotransferase system. These metabolites were further transformed into L-alanine, L-lysine, N6-Acetyl-L-lysine, (R)-b-aminoisobutyric acid, and 2-oxoarginine, through glycine, serine, and threonine metabolism, citrate cycle, D-arginine and D-ornithine metabolism, lysine degradation, and pyruvate metabolism pathways. Prokaryotic reference transcriptomics found that this may be mainly regulated by the bsh, phnE, ptsP, B0667_RS04545, and B0667_RSRS12300 genes, which was further validated by qPCR. Furthermore, molecular docking results demonstrated that 8 differential metabolites might bind to another portion of cholesterol via PI-PI conjugation and hydrophobic interactions and lower cholesterol via co-sedimentation. This study has strategic implications for developing probiotic powder food that lowers cholesterol.