Impact of Colonic Fermentation of Plant Sterol-Enriched Rye Bread on Gut Microbiota and Metabolites

Abstract

Studies on the impact of colonic fermentation of plant sterol (PS)-enriched foods using dynamic in vitro models are limited. This study aimed to evaluate the effect of a 72-h dynamic in vitro digestion-colonic fermentation (using the simgi® system) of PS-enriched rye bread on colonic microbial population and short-chain fatty acid (SCFA) and ammonium production. In all colon compartments (ascending colon (AC), transverse colon (TC), and descending colon (DC)) (72 vs. 0 h), a reduction in ammonium concentration (5.7- to 9.4-fold) and an increase in Staphylococcus spp. (1.4- to 2.1-fold), Lactobacillus spp. (1.5-fold), Bifidobacterium spp. (1.3- to 1.5-fold), and Enterococcus spp. (1.4- to 1.6-fold) were observed. In AC and TC, total SCFA decreased (4- and 1.3-fold, respectively), whereas it increased 1.4-fold in DC due to an increase in butyrate content from 4 to 45 mM. These results suggest that PS-enriched rye bread favors the growth of beneficial microbial species and the production of butyrate, a fuel source for enterocytes, thus promoting health benefits.

Keywords

• in vitro colonic fermentation
• plant sterols
• microbiota
• short-chain fatty acids
• ammonium