Fig. 4. Changes in fecal community composition in response to glycans across human donors.

Differences in relative abundances of genera in ex vivo fecal cultures grown on (a) BRF, (b) BQM, or (c) lactulose relative to no-glycan controls. Data points show median log₂FC in genus abundances for each donor; box plots show median and interquartile range across donors. Genera with significant changes (p < 0.05 after FDR correction) are shown. d Differences in CAZyme gene abundances in ex vivo cultures grown on different glycans (median log₂FC versus no-glycan controls). CAZyme family/subfamilies with significant abundance changes (p < 0.05 after FDR correction) and log₂FC > 1 on at least one glycan versus no-glycan controls are shown with hierarchical clustering based on Euclidean distance. Colors are FC with gray showing families not detected in the no-glycan control. Asterisks indicate significantly elevated abundance. a–d Fecal cultures from healthy donors (ten donors for SGs, seven donors for lactulose) were grown in triplicate for 45 h in MM29 medium supplemented with 5 g l⁻¹ glycan, as appropriate, and sequenced by metagenomics. Statistical significance for genus and CAZyme changes was determined by fitting a linear mixed-effect model on rank transformed genera/CAZyme abundance data with glycan treatment as fixed effect and subject as random effect. Source data are provided as a Source Data file. SGs Synthetic Glycans, FC fold change, FDR false discovery rate, CAZyme carbohydrate-active enzyme, GH glycoside hydrolase, CBM carbohydrate-binding modul, PL polysaccharide lyase, GT glycosyltransferase, AA auxiliary activity.