Abstract: This study aims to investigate whether Bacillus coagulans BC2000 can improve the ameliorative effect of ellagic acid (EA) on insulin resistance caused by a high-fat diet in mice and the relationship between BC2000 and gut microbiota remodeling. Fifty C57BL/6J mice were randomly divided into five groups: a low-fat diet group (LFD), a high-fat diet group (HFD), a high-fat diet with EA group (HFD + EA), a high-fat diet with EA and Bacillus coagulans BC30 group (HFD + EA + BC30), and a high-fat diet with EA and Bacillus coagulans BC2000 group (HFD + EA + BC2000). After intervention for 10 weeks, physiological and biochemical indexes and inflammatory cytokine levels were measured. In addition, histological examination of the liver and epididymal adipose tissues was performed, and the microbial community structure in cecal contents was analyzed. The results showed that the combination of BC2000 and EA improved obesity and reduced fat cell hypertrophy and liver steatosis in high-fat diet-fed mice, and significantly reduced the plasma levels of insulin, total cholesterol and low-density lipoprotein cholesterol (LDL-C) and insulin resistance index as well as the plasma levels of lipopolysaccharide (LPS), Zonulin, tumor necrosis factor (TNF)α, hypersensitive C-reactive protein (CRP) and interleukin 6 (IL-6) (P < 0.05). Moreover, the combination of BC2000 and EA improved the gut microbiota by increasing the relative abundance of Actinobacteria and Lactobacillus and decreasing the relative abundance of Desulfovibrio. Taken together, Bacillus coagulans BC2000 enhances the role of EA in regulating glucolipid metabolism and insulin resistance by modulating the gut microbiota. This study provides a theoretical basis for the application of Bacillus coagulans BC2000 as a probiotic in foods.

Key words: Bacillus coagulans; ellagic acid; high-fat diet-fed mice; gut microbiota; insulin resistance