The Screening Of Lactobacillus With Cholesterol-lowering Ability And Its Application In Vivo

Hypercholesterolemia is one of the major risk factors of cardiovascular disease and therefore reducing the body’s cholesterol is essential to human health. Researches have shown that many Lactobacillus have cholesterol-lowering effect in vitro and in vivo. Long-term consumption of dairy products containing probiotics has been proposed as a means to lower serum cholesterol and reduce the incidence of cardiovascular disease.The cholesterol-reducing ability of 28 lactic acid bacterium(LAB) strains isolated from the Kefir grain and picked vegetable was determined in vitro, after which there were 8 strains with relatively high removal rate of cholesterol were selected as candidate strains. Considering its beneficial characteristics in vitro including acid-tolerance, bile salt tolerance,hydrophobicity and removal rate of cholesterol in different culture times,3 target strains were screened. Strains with beneficial characteristics in vitro, were determined antibacterial activity, bile salt hydrolase activity and growth curve to screen the target strain. The target strain was identified as Lactobacillus plantarum DMDL9010.The cholesterol-lowering of Lactobacillus plantarum DMDL9010 in vivo was evaluated. Five treatment groups of rats(n=10) were fed experimental diets: normal diet, hypercholesterol diet(0.5 % cholesterol, w/w), hypercholesterol diet + atorvastatin(1mg/day), hypercholesterol diet+ high does of LAB(109 CFU/day) and hypercholesterol diet+ low does of LAB(107 CFU/day). Body weight, feed intake, and feed efficiency did not differ among the five groups after 10 weeks period. Supplementation with high does of LAB reduced total serum cholesterol(23.03 %) and low-density lipoprotein cholesterol content(28.00 %) significantly in hypercholesterol diet groups. What’s more, the morphological and pathological changes in the liver showed that L. plantarum DMDL9010 protected the rats against hepatocyte steatosis. Additionally, high dose of LAB also exhibited a positive cholesterol-lowering effect through decreasing the liver cholesterol(33.20 %) and triglyceride(40.86 %) and increasing fecal cholesterol(31.07 %) and bile acid excretion(70.18 %) significantly.Additionally, Quantitative real-time RT-PCR analysis of gene expression revealed that high does of L. plantarum DMDL 9010 and atorvastatin downregulated expression of 3-hydroxy-3-methylglutaryl-CoA reductase(HMGCo-A). It was suggested that L. plantarum DMDL 9010 and atorvastatin probably can suppress the synthesis of cholesterol to lower serum cholesterol. L. plantarum DMDL 9010 shows great potential as a cardiovascular disease preventive and therapeutic.