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Nat Commun. 2019 Feb 22;10(1):905. doi: 10.1038/s41467-019-08812-y.

The human gut Firmicute Roseburia intestinalis is a primary degrader of dietary β-mannans.

Author information

1
Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Aas, N-1433, Norge, Norway.
2
Dept. of Biotechnology and Biomedicine, Danish Technical University, Kgs. Lyngby, DK-2800, Denmark.
3
Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, 48109, MI, USA.
4
Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Aas, N-1433, Norge, Norway. bjorge.westereng@nmbu.no.

Abstract

β-Mannans are plant cell wall polysaccharides that are commonly found in human diets. However, a mechanistic understanding into the key populations that degrade this glycan is absent, especially for the dominant Firmicutes phylum. Here, we show that the prominent butyrate-producing Firmicute Roseburia intestinalis expresses two loci conferring metabolism of β-mannans. We combine multi-"omic" analyses and detailed biochemical studies to comprehensively characterize loci-encoded proteins that are involved in β-mannan capturing, importation, de-branching and degradation into monosaccharides. In mixed cultures, R. intestinalis shares the available β-mannan with Bacteroides ovatus, demonstrating that the apparatus allows coexistence in a competitive environment. In murine experiments, β-mannan selectively promotes beneficial gut bacteria, exemplified by increased R. intestinalis, and reduction of mucus-degraders. Our findings highlight that R. intestinalis is a primary degrader of this dietary fiber and that this metabolic capacity could be exploited to selectively promote key members of the healthy microbiota using β-mannan-based therapeutic interventions.

PMID:
30796211
PMCID:
PMC6385246
DOI:
10.1038/s41467-019-08812-y
[Indexed for MEDLINE]
Free PMC Article

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