Screening Of Cholesterol-lowering Lactic Acid Bacteria And Its Effects On Cholesterol Metabolism And Intestinal Flora In Mice High-fat Model

Cholesterol is an important part of the body,but excessive cholesterol content will cause disorder of lipid metabolism and cardiovascular and cerebrovascular diseases.Regulating cholesterol homeostasis is crucial to human health.Lactic acid bacteria as a normal intestinal flora,play an important role in regulating metabolism in human body.This study aims to screen out a lactic acid bacteria with excellent cholesterol lowering characteristics,study its effect on high-fat mice,analyze its cholesterol lowering mechanism in vivo,so as to provide a theoretical basis for the further development and utilization of lactic acid bacteria resources.A strain of lactic acid bacteria with good cholesterol-lowering properties was screened from 15 strains of lactic acid bacteria.It was identified as Lactobacillus paracasei by molecular biology and numbered CM6.The target strain was applied to the high-fat mouse model.The results showed that strain CM6 could reduce the weight gain of high-fat mice and significantly reduce the liver index of high-fat mice(P < 0.05).The contents of TC,TG and LDL-C in serum of high-fat mice decreased and the content of HDL-C increased.At the same time,the contents of TC and TG in liver of high-fat mice decreased significantly(P < 0.05),and the contents of TC and TBA in feces increased.The relative expression of ABCG5 and ABCG8 genes in HL group was significantly higher than that in NC group(P < 0.001),and the relative expression of NPC1 L1 gene was significantly lower than that in NC group(P < 0.001).The results showed that the intragastric administration of strain CM6 reduced the cholesterol content in high-fat mice and increased cholesterol efflux.The results of intestinal microbial diversity in mice showed that strain CM6 could increase the diversity and richness of intestinal microorganisms in mice and change the composition of intestinal microorganisms in mice.The intake of strain CM6 increased the abundance of Firmicutes and Lactobacillus in the intestinal of mice,decreased the abundance of Ruminococcus＿torques＿group,Allobacillus and Dubosiella,and improved the intestinal microbial structure of high-fat mice.Metabonomics analysis showed that strain CM6 changed the liver metabolites of high-fat mice,and affected taurine and taurine metabolism,retinol metabolism,PPAR signaling pathway and other metabolic pathways.The correlation analysis between microbial diversity and metabolomics showed that the abundance changes of Allobaculum,Lactobacillus and Enterorhabdus were related to the relative abundance of taurine,cholic acid,L-glutamic acid and 9-cis-retinoic acid in the liver.In conclusion,strain CM6 can reduce the cholesterol content in high-fat mice,and regulate the composition of intestinal flora and liver metabolites.The mechanism of its regulation of cholesterol in vivo may be by reducing the absorption of cholesterol in the intestine,increasing the efflux of cholesterol in the intestine,and possibly by mediating the abundance of Allobaculum and Lactobacillus and Enterorhabdus in the small intestine of hypercholesterolemic mice.and affects the relative abundance of taurine,cholic acid,Lglutamic acid,and 9-cis-retinoic acid in the liver of mice,which can increase the decomposition of cholesterol in the liver,thereby reducing the cholesterol content in mice with high cholesterol.