Complex Probiotics Ameliorate Fecal Microbiota Transplantation-Induced IBS in Mice via Gut Microbiota and Metabolite Modulation

<b>Background/Objectives:</b> Irritable bowel syndrome (IBS) is a highly prevalent functional gastrointestinal disorder. Emerging evidence implicates gut microbiota dysbiosis in IBS pathogenesis, and probiotic interventions targeting microbial modulation hold therapeutic promise. <b>Methods:</b> this study used fecal microbiota transplantation to establish a mouse model of IBS before evaluating the effects of the complex probiotic by using metagenomics and targeted metabolomics to explore the potential mechanism. <b>Results:</b> After 14 days, the probiotic relieved constipation, reduced inflammation and intestinal permeability, lowered 5-HT levels and increased serotonin transporter (SERT) expression in tissues. Metagenomic analysis showed a reduced inflammation-related species abundance. It also decreased fecal butyric acid, acetic acid and tryptophan levels in IBS mice. <b>Conclusions:</b> The probiotic complex effectively alleviated IBS symptoms in mice by modulating gut microbiota and fecal metabolites, providing insights for future IBS research and treatment.