Fig. 7: Condensed tannin alone can stimulate growth of Faecalibacterium prausnitzii.

a Dot plots of absolute abundance of Faecalibacterium prausnitzii  by qPCR in microbiome or pure culture of Faecalibacterium prauznitzii A2-165 with fermentation media alone or fermentation media supplemented with quebracho tree condensed tannin extract. Five microbiomes showing the most significant difference between tannin-positive RIL pool and non-tannin RILs pools were chosen, and qPCR was run on the baseline (after introduction of the stool samples) and on the samples after 16 h of incubation. The absolute level of pure culture F. prausnitzii A2-165 for the baseline (after inoculation with F. prausnitzii A2-165) and after 48 h of incubation was also determined using qPCR (n = 3 for each group). Data are presented as mean values ± SEM. Different letters (a–c) indicate significant difference among different treatment groups determined by two-sided one way ANOVA corrected by Benjamini–Hochberg pairwise comparisons (p < 0.05). b Evaluation of tannin utilization activity of F. prauznitzii A2-165 in agar overlay assay. LYBHI media was supplemented with 1% agar and a pure culture of F. prausnitzii was streaked onto the media for isolated colonies (top portion of petri dish) or in a patch (bottom portion of the plate). After 24 h of anaerobic incubation, the culture was overlayed with fermentation media supplemented with 1% agar and quebracho tree tannin. The culture was then incubated for an additional 48 h. Areas of clearing around individual colonies and the patched growth indicated degradation of the brown-colored tannin. Source data are provided as a Source Data file.