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Sci Rep. 2017 Jan 16;7:40248. doi: 10.1038/srep40248.

A fibrolytic potential in the human ileum mucosal microbiota revealed by functional metagenomic.

Author information

1
Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France.
2
Metagenopolis, INRA, 78350 Jouy-en-Josas, France.
3
Plate-forme bio-informatique Genotoul, Mathématiques et Informatique Appliquées de Toulouse, INRA, Castanet-Tolosan, France.
4
CNRS UMR 7257, Université Aix-Marseille, 13288 Marseille, France.
5
INRA, USC 1408 AFMB, 13288 Marseille, France.
6
Department of Biological Sciences, King Abdulaziz University, Jeddah, Saudi Arabia.

Abstract

The digestion of dietary fibers is a major function of the human intestinal microbiota. So far this function has been attributed to the microorganisms inhabiting the colon, and many studies have focused on this distal part of the gastrointestinal tract using easily accessible fecal material. However, microbial fermentations, supported by the presence of short-chain fatty acids, are suspected to occur in the upper small intestine, particularly in the ileum. Using a fosmid library from the human ileal mucosa, we screened 20,000 clones for their activities against carboxymethylcellulose and xylans chosen as models of the major plant cell wall (PCW) polysaccharides from dietary fibres. Eleven positive clones revealed a broad range of CAZyme encoding genes from Bacteroides and Clostridiales species, as well as Polysaccharide Utilization Loci (PULs). The functional glycoside hydrolase genes were identified, and oligosaccharide break-down products examined from different polysaccharides including mixed-linkage β-glucans. CAZymes and PULs were also examined for their prevalence in human gut microbiome. Several clusters of genes of low prevalence in fecal microbiome suggested they belong to unidentified strains rather specifically established upstream the colon, in the ileum. Thus, the ileal mucosa-associated microbiota encompasses the enzymatic potential for PCW polysaccharide degradation in the small intestine.

PMID:
28091525
PMCID:
PMC5238381
DOI:
10.1038/srep40248
[Indexed for MEDLINE]
Free PMC Article

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