Short-Term Supplementation of Pectin Alters Substrate Dynamics and Modulates Microbial Carbohydrate Metabolism in the Gut of a Pig Model

The interaction of pectin and gut microbiota plays an important role in maintaining animal and human health, but this interaction is not fully understood. Here, the impact of pectin supplementation on substrate dynamics and gut microbiota (in the terminal ileum and feces) was integrally investigated in a fistula pig model. Our results showed that a pectin-supplemented diet (PEC) decreased the concentrations of starch, cellulose, and butyrate in feces but not in the terminal ileum. Metagenomic sequencing revealed that PEC had a low impact on the ileal microbiota but significantly increased plant polysaccharide-degrading genera (e.g., Bacteroides, Alistipes, and Treponema) in feces. Additionally, CAZyme profiling indicated that PEC reduced GH68 and GH8 for oligosaccharide degradation in the ileal microbiome, while it enriched GH5, GH57, and GH106 for degradation of carbohydrate substrates in feces. Metabolomic analysis confirmed that PEC increased metabolites involved in carbohydrate metabolism including glucuronate and aconitate. Collectively, pectin could promote complex carbohydrate substrate degradation in the hindgut via modulating the gut microbiota.