Mechanism Of Acid Tolerance Of Lactiplantibacillus Plantarum ZDY2013 And Study On Its Alleviation Effect On Diet-induced Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease(NAFLD)is a common chronic liver disease making an impact on the health of people in an increasing rate,which is characterized by excessive fat accumulation(with fat infiltration>5%of hepatocytes)in the liver without evident alcohol consumption.Lactiplantibacillus plantarum ZDY2013 is a L.plantarum screened from fermented soybeans.In the previous research,it can be concluded that L.plantarum ZDY2013 can improve intestinal flora,and has the ability of acid resistance,antioxidation and anti-inflammation.In this paper,the whole genome and comparative transcriptome sequencing were used to analyze the mechanism of acid tolerance,and NAFLD mice model induced by long-term high-fat,high-fructose and high-cholesterol diet(HFFC)was established,and then intragastric administration of Lactobacillus plantarum ZDY2013 was used to detect its relieving effect on diet-induced NAFLD symptoms and explain its potential mechanism.The full text is divided into five chapters.The first chapter is introduction,which describes non-alcoholic fatty liver disease and probiotics.In the second chapter,the acid tolerance mechanism of L.plantarum ZDY2013was analyzed based on the whole genome and comparative transcriptome sequencing.According to the results of whole genome analysis,the genome size of L.plantarum ZDY2013 was 3304282 bp,and the GC content was 45.68%.A total of 3145 genes were predicted,including 64 t RNA,16 r RNA and 1 s RNA gene,and genes related to carbohydrate transport and metabolism,proteolytic enzyme system and amino acid biosynthesis,stress response and adhesion were found.Compared with CK group(L.plantarum ZDY2013 cultured in normal MRS medium),there were 310 up-regulated genes and 342 down-regulated genes in SCL group(L.plantarum ZDY2013 cultured in p H 3.0 MRS medium).Under acidic conditions,there were significant differences in ABC transporter,phosphotransferase system and amino acid metabolism between CK group and SCL group,which were related to H~+-ATPase pathway.The results of KEGG classification also showed that there were significant differences in fructose and mannose metabolism,glycolysis/gluconeogenesis,galactose metabolism,and starch and sucrose metabolism between CK group and SCL group,which can provide a large amount of ATP for proton pump excretion of H~+.These results suggest that the acid resistance response of ZDY2013 may be realized by H~+-ATPase pathway.In the third chapter,we examined the alleviating effect of L.plantarum ZDY2013on NAFLD by HFFC diet.The diet-induced NAFLD mice model was established,and the mice were given intragastric administration of L.plantarum ZDY2013.After modeling,the body damage caused by HFFC diet and the alleviating effect of L.plantarum ZDY2013 on tissue damage induced by HFFC diet were detected.The results showed that HFFC diet caused intestinal flora disorder and inflammation,destroyed intestinal barrier,and led to the leakage of lipopolysaccharide(LPS)into serum,resulting in liver inflammation,disorder of liver lipid metabolism,increase of lipid accumulation,and damage of liver function.The intervention of L.plantarum ZDY2013 significantly regulated intestinal flora and inflammation,repaired intestinal barrier,thereby resulting in reduced liver inflammation and fat accumulation.The fourth chapter summarizes the acid-resistant mechanism of L.plantarum ZDY2013 based on the whole genome and comparative transcriptome sequencing,and its relieving effect on diet-induced NAFLD by regulating intestinal flora,and the follow-up research was prospected.In this paper,the acid-resistant mechanism of L.plantarum ZDY2013 was analyzed by whole genome and transcriptome sequencing,and the possible mechanism of relieving diet-induced NAFLD was explored,in order to provide basic data and theoretical support for probiotic-assisted intervention to alleviate fatty liver.