Deciphering synergistic mechanisms and therapeutic potential of bacteroides ovatus and pectin in functional constipation

Functional constipation (FC), a common bowel disorder disease worldwide. Recent studies have noted impaired gastrointestinal motility is associated with gut dysbiosis in FC. Through shotgun metagenomic sequencing of 153 Hong Kong residents (69 FC patients and 84 healthy controls), we identified significant alterations in gut microbial composition and functional capacity, particularly in carbohydrate metabolism. Here, we predicted genes encoding carbohydrate-active enzymes in microbial genomes. Our analysis revealed a substantial depletion of pectin-degrading polysaccharide utilization loci (PULs) and a marked reduction (p < 0.001) in Bacteroides ovatus abundance - a key polysaccharide-degrading bacterium encoding multiple PULs essential for dietary fibre metabolism. Notably, pectin-degrading PULs were predicted as the most abundant dietary fibre-degrading PULs in the B. ovatus genome and the abundance of B. ovatus were significantly positively correlated (p<0.001, r=0.3) with the overall abundance of pectin-degrading PULs in the metagenome. These microbial features showed positive correlations (p < 0.01) with spontaneous bowel movement frequency, suggesting their crucial role in intestinal health. The combination of B. ovatus and pectin may serve as a potential therapeutic approach for the treatment of FC. In vivo experiments demonstrated that a 14-day B. ovatus supplementation effectively alleviated loperamide induced constipation in mice by defecation frequency and whole gut transit time. While citrus peel-derived pectin alone showed limited efficacy, its combination with B. ovatus produced synergistic effects, significantly enhancing therapeutic outcomes. These findings establish a mechanistic link between B. ovatus-mediated pectin metabolism and FC symptomology, providing a scientific foundation for developing targeted probiotic therapies based on microbial genomic features. The demonstrated synergy between specific bacterial strains and dietary fibres offers new possibilities for personalized microbiome-based interventions in gastrointestinal disorders.