Source of plant proteins diverts colonic fermentation of wheat arabinoxylan

The substitution of plant proteins for animal proteins in food production is an emerging trend. Although various plant proteins are available, limited information exists regarding their colonic fermentation properties. In this study, we aimed to assess how the undigested fraction of plant protein, in the presence of dietary fiber, affects gut microbiota composition and metabolic outputs. Six plant protein isolates (pea, chickpea, mung bean, soybean, lentil, and brown rice) and a milk protein concentrate were digested using the INFOGEST model, and undigested residues were collected. These protein residues were then co-fermented with wheat arabinoxylan in a fecal microbial fermentation system. The results showed that all protein-treated cultures elevated propionate synthesis that the molar ratio of propionate increased from 17% to 25–32%. Protein supplementation enhanced the relative abundance of Bacteroidetes, exemplified by species Bacteroides plebeius, whose relative abundance increased to 45–50% under brown rice, chickpea, and pea protein treatments. Diversified responses were observed within Firmicutes populations. Members of the Lachnospiraceae family, including genera Blautia , Eubacterium , and Fusicatenibacter , decreased, whereas Lachnoclostridium increased under pea, chickpea, lentil, and milk protein treatments. The genera Megasphaera and Megamonas from the family Veillonellaceae were enriched under mung bean and brown rice protein treatments. Furthermore, the genus Phascolarctobacterium in the family Acidaminococcaceae was enriched under chickpea and lentil protein treatments. This study highlights the phenomenon of Bacteroidetes enrichment and propionate production during the colonic fermentation of protein residues and reveals discrete Firmicutes responses in the presence of wheat arabinoxylan. • Undigested plant protein residues were co-fermented with wheat arabinoxylan. • Propionate yields were enhanced in all protein-supplemented treatments. • Bacteroidetes enriched by proteins, were represented by Bacteroides plebeius. • Supplementing protein residues triggered diversified responses within Firmicutes. • Observed major species may participate in both fiber and protein metabolism.