Human gut Bacteroidetes can utilize yeast mannan through a selfish mechanism

Nature. 2015 Jan 8;517(7533):165-169. doi: 10.1038/nature13995.


Yeasts, which have been a component of the human diet for at least 7,000 years, possess an elaborate cell wall α-mannan. The influence of yeast mannan on the ecology of the human microbiota is unknown. Here we show that yeast α-mannan is a viable food source for the Gram-negative bacterium Bacteroides thetaiotaomicron, a dominant member of the microbiota. Detailed biochemical analysis and targeted gene disruption studies support a model whereby limited cleavage of α-mannan on the surface generates large oligosaccharides that are subsequently depolymerized to mannose by the action of periplasmic enzymes. Co-culturing studies showed that metabolism of yeast mannan by B. thetaiotaomicron presents a 'selfish' model for the catabolism of this difficult to breakdown polysaccharide. Genomic comparison with B. thetaiotaomicron in conjunction with cell culture studies show that a cohort of highly successful members of the microbiota has evolved to consume sterically-restricted yeast glycans, an adaptation that may reflect the incorporation of eukaryotic microorganisms into the human diet.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Bacteroidetes / cytology
  • Bacteroidetes / enzymology
  • Bacteroidetes / genetics
  • Bacteroidetes / metabolism*
  • Biological Evolution
  • Carbohydrate Conformation
  • Diet
  • Enzymes / genetics
  • Enzymes / metabolism
  • Female
  • Gastrointestinal Tract / microbiology*
  • Genetic Loci / genetics
  • Germ-Free Life
  • Glycoproteins / chemistry
  • Glycoproteins / metabolism
  • Humans
  • Male
  • Mannans / chemistry
  • Mannans / metabolism*
  • Mannose / metabolism
  • Mice
  • Models, Biological*
  • Models, Molecular
  • Oligosaccharides / chemistry
  • Oligosaccharides / metabolism
  • Periplasm / enzymology
  • Yeasts / chemistry*


  • Enzymes
  • Glycoproteins
  • Mannans
  • Oligosaccharides
  • Mannose

Associated data

  • PDB/4C1R
  • PDB/4C1S
  • PDB/4UTF