title: Wheat bran promotes enrichment within the human colonic microbiota of butyrate-producing bacteria that release ferulic acid.
abstract: Cereal fibres such as wheat bran are considered to offer human health benefits via their impact on the intestinal microbiota. We show here by 16S rRNA gene-based community analysis that providing amylase-pretreated wheat bran as the sole added energy source to human intestinal microbial communities in anaerobic fermentors leads to the selective and progressive enrichment of a small number of bacterial species. In particular, OTUs corresponding to uncultured Lachnospiraceae (Firmicutes) related to Eubacterium xylanophilum and Butyrivibrio spp. were strongly enriched (by five to 160 fold) over 48 h in four independent experiments performed with different faecal inocula, while nine other Firmicutes OTUs showed > 5-fold enrichment in at least one experiment. Ferulic acid was released from the wheat bran during degradation but was rapidly converted to phenylpropionic acid derivatives via hydrogenation, demethylation and dehydroxylation to give metabolites that are detected in human faecal samples. Pure culture work using bacterial isolates related to the enriched OTUs, including several butyrate-producers, demonstrated that the strains caused substrate weight loss and released ferulic acid, but with limited further conversion. We conclude that breakdown of wheat bran involves specialist primary degraders while the conversion of released ferulic acid is likely to involve a multi-species pathway.
authors.affiliation: Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK.
authors.forename: Sylvia H
authors.initials: SH
authors.lastname: Duncan
authors.affiliation: Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK.
authors.forename: Wendy R
authors.initials: WR
authors.lastname: Russell
authors.affiliation: Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Quartieri
authors.affiliation: Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Maddalena
authors.initials: M
authors.lastname: Rossi
authors.affiliation: Pathogen Genomics Group, Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire, UK.
authors.forename: Julian
authors.initials: J
authors.lastname: Parkhill
authors.affiliation: Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK.|Pathogen Genomics Group, Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire, UK.
authors.forename: Alan W
authors.identifier: 0000-0001-5099-8495
authors.initials: AW
authors.lastname: Walker
authors.affiliation: Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK.
authors.forename: Harry J
authors.initials: HJ
authors.lastname: Flint
mesh_terms: D000328:Adult; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D019149:Bioreactors; D002087:Butyrates / Q000378:metabolism*; D003106:Colon / Q000378:metabolism / Q000382:microbiology*; D003373:Coumaric Acids / Q000378:metabolism*; D004043:Dietary Fiber / Q000378:metabolism*; D005243:Feces / Q000382:microbiology; D005260:Female; D000069196:Gastrointestinal Microbiome; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000382:microbiology; D008297:Male
chemical_list: D002087:Butyrates; D003373:Coumaric Acids; D004043:Dietary Fiber; C004999:ferulic acid