The effect of dietary fibre composition and complexity on human gut microbial communities

This study assessed the effect of different dietary fibres (DF) on bacterial growth, production of fermentation acids, and community composition, using in vitro batch cultures inoculated with faecal slurry from three healthy donors. High growth on apple, beetroot, carrot, and kale, and relatively low growth on beet leaves and wheat bran were seen for all donors. The substrates had a stronger influence on community composition at the genus level than faecal-donor (44% vs 35). When the donors were assessed individually, clear clustering patterns based on cell-wall type (grain vs non-grain), were observed. Several differential abundant genera were identified, mainly associated with xylan degradation for wheat bran (Eubacterium xylanophilum group) and pectin degradation for the non-grain substrates (Lachnospira eligens group and Monoglobus). Clustering patterns between the non-grain substrates were also seen with accompanying differential abundant genera. All donors produced relatively similar communities from apple, carrot, and kale, and more distinct communities from the beet substrates.