Bacillus amyloliquefaciens SC06 alleviates obesity of ob/ob mice by improving intestinal microbiota and bile acid metabolism via the FXR signaling pathway

Dietary interventions with probiotics were widely reported to be effective to regulate obesity, and intestinal microbiota was considered as an important environmental factor. However, few reports focus on the microbiota-metabolites-phenotypic variables interactions in ob/ob mice, and have not been characterized in great details. In this study, we investigated the effects of Bacillus amyloliquefaciens SC06 on obesity, intestinal microbiota and bile acids metabolism of ob/ob mice by using biochemical testing, histochemical stain, high-throughput sequencing of 16S rRNA gene LC-MS/MS analysis and qRT-PCR. The results showed that SC06 ameliorated fat mass percentage, hepatic steatosis and liver lipid metabolism disorders and reshaped the gut microbiota and metabolites in male ob/ob mice, specifically deceasing in f_S24-7, p_TM7, s_Alistipes massiliensis, f_Rikenellaceae, f_Prevotellaceae, f_Lactobacillaceae, g_Alistipes, g_Flexispira, g_Lactobacillus, g_Odoribacter, g_AF12 and g_Prevotella and increasing in f_Bacteroidaceae, g_Bacteroides and f_Desulfovibrionaceae. Meanwhile, SC06 treatment groups had lower Ibuprofen and higher Glycodeoxycholic acid and 7-Dehydrocholesterol. Correlation analysis further clarify relationships between compositional changes in microbiota and alterations in the metabolites and phenotypes of ob/ob mice. Moreover, SC06 downregulated bile acid synthesis, export and re-absorption in liver, and increase ileum re-absorption into the blood in ob/ob mice, which may be mediated by FXR-SHP / FGF15 signaling pathway. These results suggested that Bacillus amyloliquefaciens could ameliorate obesity in male ob/ob mice by reshaping the intestinal microbial composition, changing metabolites and regulating bile acid metabolism via the FXR signaling pathway.