In vitro colonic fermentation of a plant sterol-enriched beverage in a dynamic-colonic gastrointestinal digester

Abstract The impact of a plant sterol-enriched beverage on the sterol metabolism, organic acid production and microbiota composition was evaluated by means of a dynamic gastrointestinal and colonic fermentation model. After one week of fermentation, an absence of sterol metabolites was reported, in accordance with the lack of microbiota related to their metabolism. Although total organic acid content was lower in the ascending colon (AC) compared to the transversal (TC) and descending colon (DC) (28-57 mmol/L vs. 55-87 and 44-64 mmol/L, respectively), its increments, with respect to the initial value, were higher (2-fold vs. 1.6- and 1.5-fold). Increments of acetate, butyrate and propionate were observed in all colon vessels, whereas lactate production was only observed in the AC at the first hours of fermentation. Results showed a progressive increase in microbial species richness and evenness from the AC to the DC. Beverage fermentation also modulated certain members of the microbiota: Bifidobacterium (within 24 hours) and Megasphaera genera were stimulated, and Mitsuokella was reduced in AC, while the growth of Klebsiella genus was promoted and Bacteroidetes phylum decreased in TC and DC. These results show that the beverage modulates the microbial community and activity, which could be physiologically relevant to the host.