Bifidobacterium animalis subsp. lactis BL-99 with fructo-oligosaccharide alleviates constipation in mice by modulating gut microbiota

AbstractConstipation, a widespread gastrointestinal condition, significantly impairs life quality and health. Recent advancements in modulating gut microbiota through prebiotics, probiotics, and synbiotics have unveiled new therapeutic possibilities. In this study, metagenomic and non-target metabolomics techniques were used to evaluate the effects of Bifidobacterium animalis subsp. lactis BL-99 (BL-99), fructooligosaccharide (FOS), and a synbiotic combination of BL-99 and FOS (BL-99+FOS) on constipated mice. Mice were divided into six groups, including control, loperamide-induced constipated model, BL-99, FOS, BL-99+FOS, and positive control (POS) groups. Our results showed that BL-99, FOS, and BL-99+FOS each alleviated constipation, with the synbiotic showing significant efficacy in first black stool defecation time and gastrointestinal transit rate (P < 0.05). Additionally, significant increased in serum 5-HT and IL-10 were observed in the BL-99+FOS group, alongside an increased relative abundance of Lachnospiraceae_NK4A136_group, Blautia, and Clostridium sensu stricto 1, while significantly reducing the relative abundance of Alistipes and Bacteroides. These changes facilitated alterations in bile acid (BA) and short-chain fatty acids (SCFAs) metabolism. And these changes were closely associated with the expression of genes related to the 5-HT pathway and the modulation of serum inflammatory factors. This study provides a theoretical basis for synbiotic to improve constipation by regulating the gut microbiota and metabolites.