Polyphenols non-covalently bound to artificial plant cell walls are readily accessible to fecal microbiota and transiently alter fermentation activity

This study aimed to elucidate three-way interactions among dietary fiber, polyphenols (PPs), and the gut microbiota at physiologically relevant concentrations. A three-component bacterial cellulose analogue of the apple cell wall (aACW) soaked in a PP extract from apples (aACW + PP) was produced and gut microbial responses were tested using in vitro fecal microbiota batch fermentations of five donors. Soaking left ∼17 % of PPs bound to aACWs, with flavonols being the most retained. Several flavonoids were detected early during aACW + PPs in vitro fecal fermentation and were rapidly metabolized with differences between individual fecal microbiota. aACW-bound PP increased fermentation activity, as indicated by higher acetic acid and lower formic acid levels after 5 h of fermentation. Beta-diversity analysis identified donor individuality as a stronger determinant of microbiota composition than treatment. Baseline interindividual microbiota composition emerged as the dominant factor shaping both PP metabolism and microbial community trajectories under the tested, physiologically relevant concentrations.