Dominant Gut Commensals Enriched by Pectin with Low Esterification Degree Orchestrate the Amelioration of Acute Ulcerative Colitis

Dietary fiber's health benefits are increasingly recognized as microbiota-dependent, with effects influenced by fiber structure. We previously observed that low-esterified pectin provides superior protection against DSS-induced colitis compared to its high-esterified form, but the mechanism was unknown. This study investigated the microbiota-dependent pathway underlying low-esterified pectin's anticolitic effect using FMT. By evaluating three pectin-induced bacteria (Bifidobacterium longum NSP002, Bacteroides xylanisolvens NSP003, Enterococcus faecium NSP004) individually and in a consortium, we found that the consortium exerted a significantly stronger protective effect, suggesting synergistic interactions and highlighting its potential as an FMT alternative. Mechanistically, this protection may involve three axes: (1) Gut microbiome remodeling (reduced Akkermansia, increased Bacteroides, elevated propionic acid). (2) Intestinal homeostasis modulation (reduced mme/calprotectin expression, activated PI3K/calcium signaling). and (3) Systemic metabolic reprogramming (increased serum phenylethylamine, enriched phenylalanine metabolism). These findings support the clinical potential of pectin for optimizing enteral nutrition and using pectin-enriched microbiota consortia to target IBD pathogenesis.