Screening Of Lactobacillus With Probiotic Properties From Traditional Fermented Food In Hainan And Study On The Correlation Of Its Preventive Mechanism Of Hyperlipidaemia

Hainan province,located at the southernmost tip of China,is rich in unique tropical microbial resources.The residents of Hainan have inhabited the island for generations and have ample experience in using environmental microbes to produce various fermented foods for a long time.As the traditional fermented food loved by the people in Hainan,traditional fermented vegetables and Yucha have naturally become the best model for investigating tropical microbial diversity and the source of benefcial microbes.In the early stage,we applied high-throughput sequencing and culture-dependent technology to describe the diversity of microbiota and identify benefcial microbes in 36 fermented vegetables and 24 Yucha collected from different areas of Hainan province.The results indicated that,at the genus level,Lactobacillus was the most abundant genus,and Lactobacillus plantarum exists in the fermented food of each region with the highest content,which is the dominant species in Hainan traditional fermented food.Based on the analysis of ? and ? diversity of microbial communities,the results showed that there were significant differences in microbial community structure among Yucha in different areas,and the effect of different vegetable species on microbial community structure was greater than that of region.The functional characteristics predicted by PICRUSt indicated that the metabolic pathway in Hainan traditional fermented food was rich,which means that the microbial metabolism tended to be active.Combined with culture-dependent technology,500 strains of lactic acid bacteria(353 strains in fermented vegetables and 147 strains in Yucha)were isolated from Hainan traditional fermented food.A beneficial microbe,Lactobacillus plantarum HNU082 was initially obtained by testing the tolerance to acid and bile,and its whole genome has also been completely sequenced.Through the interpretation of its complete genome sequencing and its physiological characterization,it is fully demonstrated that it has enormous potential as a probiotic.Hyperlipidaemia is a typical chronic disease,which is caused by abnormal lipid metabolism or transport of the body,resulting in excessive increase of lipid levels in plasma or serum,and can induce a variety of cardiovascular diseases.As a metabolic disease,the occurrence of hyperlipidaemia is closely related to the metabolic disorder of the intestinal microbiome.Currently,researchers have shifted their focus to the intestinal microbiota of the host as the hyperlipidaemia therapeutic target due to the side effects and relative costs of drug therapy are quite high.Several studies have reported the relationship between intestinal microbiota and hyperlipidaemia,however,the probiotic-derived alteration of the intestinal microbiome and the metabolites related to the preventive mechanism of hyperlipidaemia have not been discovered.In the present research,metagenome based on high-throughput sequencing combined with real time q-PCR technology were applied to perform an 8-week experiment with thirty 6-week-old Sprague-Dawley rats(control group:conventional diet,n=8;hyperlipidaemia group:high-fat diet,n=8;probiotic group:high-fat diet+1 g bacterial powder daily,consisting of 8.0 log10 CFU of HNU082,n=14,day 0 to 28).The results indicated that the amount of high-density lipoprotein cholesterol(HDL-C)in probiotic group was higher than that in hyperlipidaelia group,whereas the amounts of triglycerides(TG),total cholesterol(TC)and low-density lipoprotein cholesterol(LDL-C)were significantly lower than hyperlipidaelia group.The consumed Lactobacillus plantarum HNU082 could colonize in the host intcstine for at least 8weeks.The principal coordinate analysis(PCoA)based oin Unifrac drstance revealed that the structure of intestinal microbiota in hyperlipidaemia group was dramatically altered,and the consumption of Lactobacillus plantarum HNU082 regulated the deviation.At the genus level,the contents of Bifidobacterium,Lactobacillus,Akkermansia and Faecalibacterium were makedly increased in probiotic group,while the genera Clostridium,Natranaerovirga and Odoribacter were markedly increased in hyperlipidaemia group.For the metabolic pathways,control group and probiotic group were rich in pyruvate metabolism,glycerolipid metabolism,propanoate metabolism,and fatty acid biosynthesis,whereas the hyperlipidaemia group was rich in secondary bile acid biosynthesis and lipopolysaccharide biosynthesis.Through the construction of a network among intestinal microbiota,blood indexes,metabolic pathways and Lactobacillus plantarum HNU082,we more intuitively observed the potential mechanism of hyperlipidaemia prevention.Ultilately,we believed that,Lactobacillus plantarum HNU082 can affect the intestinal microbial community,lead to the regulation of microbial functional metabolic,then regulate the blood physiological indicators of the host,and finally achieve the goal of preventing hyperlipidmia.The present study will improve our understanding of the potential probiotic mechanism in the treatment of hyperlipidaemia,and offer new view for the design and application of functional food containing probiotics.