Abstract: Objective: To screen 29 Lactobacillus strains isolated from kefir grains and fermented pickles for cholesterol-lowering activity and to explore the mechanism of action of the selected isolates in degrading serum cholesterol in rats. Methods: One of these isolates, identified as Lactobacillus plantarum DMDL 9010, was selected for its acid resistance, bile salt tolerance, hydrophobicity, bile salt hydrolase activity and cholesterol-lowering property. A feeding experiment was conducted on fifty eight-week-old Sprague Dawley rats, which were randomly divided into normal diet control, hyperlipidaemic diet control, positive (atorvastatin calcium) control, high-dose and low-dose DMDL 9010 groups. The rats were fed for 10 weeks. The serum levels of total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C) were determined on the 28th and 70th day of the experiment. The real-time fluorescence reverse transcription PCR was used to detect the expression level of 3-hydroxy-3-methylglutaryl-CoA reducase (HMGCR) as the rate-limiting enzyme for cholesterol synthesis. Results: L. plantarum DMDL 9010 was capable of 37.58% degradation of cholesterol and showed 35.48% tolerance to bile salt and a hydrophobicity of up to 40%. It had good acid resistance. A hypercholesterolemic rat model was successfully constructed after feeding a high-cholesterol diet for 28 days. Administration of high-dose DMDL 9010 for 70 days significantly reduced serum TC (23.03%) and LDL-C (28.00%), but there was no significant difference between the low-dose and positive control groups. The positive control and high-dose groups significantly down-regulated the expression level of HMG-CoA mRNA in the liver (79.92% and 62.86%, respectively) (P < 0.05). Conclusion: It is possible to develop L. plantarum DMDL 9010 into a functional microecological agent.

Key words: cholesterol-lowering, Lactobacillus, isolate, identification, HMGCR