Impact of pectin structural diversity on gut microbiota: A mechanistic exploration through in vitro fermentation

Pectins have demonstrated significant prebiotic potential in modulating gut microbiota and enhancing microbial metabolic functions. Nevertheless, the exact relationship between pectin structure and related properties on gut microbiota regulation is yet to be fully elucidated. To explore this, the interactions between four purified pectins with specific structural characteristics and gut microbiota were examined and compared through in vitro fecal fermentation, followed by full-length 16S rRNA gene sequencing, metabolomics, and bioinformatic analysis. The result shows that the pectins selectively modulated the composition of gut microbiota while being degraded into different levels of SCFAs. Moreover, the metabolite profiles in the pectin groups were also qualitatively and quantitatively different, suggesting that the structural variations in pectins further impacted the metabolic functionality of gut microbiota. The bioinformatic analysis revealed that various structural parameters of pectins, including the α-(1 → 4)-linked galacturonic acid composed linear chain in smooth region, arabinose residue determined hair region contribution, conjugated protein content, and molecular weight, are crucial factors in controlling their interaction with gut microbiota, the bacterial cross-feeding, and finally the microbial metabolic outcomes. This research advances our current understanding of the connection between pectin structure and its regulatory properties on gut microbiota at the level of purified pectin molecules.