Abstract:This paper was to explore the inhibitory effect of Lɑctobɑcillus delbrueckii KY20 and its exopolysaccharide（EPS）on obesity in mice fed with high-fat diet.The growth rate and the acid and bile salt resistance of KY20 were measured,and its EPS was extracted and purified. The obese mice model was established by highfat diet,and the mice were divided into normal group,model group,KY20 group and low-,medium-and highdose EPS groups.The weight of mice was recorded regularly after continuous gavage for 12 weeks,and glucose tolerance（GTT）,insulin tolerance（ITT）and organ index were determined. The liver and adipose tissue changes were observed with HE staining. The antibodies to glutamic decarboxylase（GADAb）,islet cell antibodies（ICA）,autoantibodies to insulin（IAA）,and tyrosine phosphatase-like protein IA-2（IA-2A）,as well as triglyceride（TG）,total cholesterol（TC）,low-density lipoprotein-cholesterol（LDL-C）,and high-density lipoprotein-cholesterol（HDL-C）were detected with the kits. Gas chromatography was performed to detect the short chain fatty acids（SCFAs）in the caecum contents of mice. The results showed that L. delbrueckii KY20 had strong acid and bile salt tolerance,and was sensitive to penicillin and gentamicin. KY20 and its EPS reduced the weight of obese mice,improved the disorder of blood lipid metabolism,and effectively inhibited obesity induced by high-fat diet.