Beyond purified dietary fibre supplements: compositional variation between cell wall fibre from different plants influences human faecal microbiota activity and growth in vitro

Michael Solvang, Freda Farquharson, Dayan Sanhueza, Graham Horgan, Wendy Russell, Petra Louis* (Corresponding Author)

*Corresponding author for this work

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Dietary fibre is a major energy source for the human gut microbiota, but it is unclear to what extent the fibre source and complexity affect microbial growth and metabolite production. Cell wall material and pectin were extracted from five different dicotyledon plant sources, apples, beet leaves, beetroots, carrots
and kale, and compositional analysis revealed differences in the monosaccharide composition. Human faecal batch incubations were conducted with 14 different substrates, including the plant extracts, wheat bran and commercially available carbohydrates. Microbial activity was determined for up to hours by measuring gas and fermentation acid production, total bacteria (by qPCR) and microbial community composition by 16S rRNA amplicon sequencing. The more complex substrates gave rise to more microbiota variation compared to the pectins. The comparison of different plant organs showed that the leaves (beet leaf and kale) and roots (carrot and beetroot) did not give rise to similar bacterial communities. Rather, the compositional features of the plants, such as high arabinan levels in beet and high galactan levels in carrot, appear to be major predictors of bacterial enrichment on the substrates. Thus, in-depth knowledge on dietary fibre composition should aid the design of diets focused on optimising the microbiota.
Original languageEnglish
Pages (from-to)1484-1504
Number of pages21
JournalEnvironmental Microbiology
Issue number8
Early online date28 Mar 2023
Publication statusPublished - 1 Aug 2023

Bibliographical note

Michael Solvang was funded by a Scottish Government Rural and Environment Science & Analytical Services (RESAS) PhD studentship and Freda Farquharson, Graham Horgan, Wendy Russell and Petra Louis also received financial support from RESAS. We would like to thank Sylvia Duncan for the gift of the wheat bran material, Donna Henderson at the Analytical Services Division of the Rowett Institute for carrying out part of the compositional analysis of substrates and short-chain fatty acid analysis, the Centre for Genome Enabled Biology and Medicine at the University of Aberdeen for 16S rRNA amplicon sequencing, Sophie Shaw for help and advice on bioinformatics analysis and Stephen Fry for training in carbohydrate analysis. The authors would like to acknowledge the support of the Maxwell Compute Cluster funded by the University of Aberdeen.

Data Availability Statement

Data availability
The processed data that supports the findings of this study are available in the supplementary material of this article, raw data not provided are available from the corresponding author upon reasonable request. Sequence data have been deposited in the National Center for Biotechnology Information sequence read
archive (NCBI SRA) under accession numbers PRJEB48569


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