Active and secreted IgA-coated bacterial fractions from the human gut reveal an under-represented microbiota core

Sci Rep. 2013 Dec 17;3:3515. doi: 10.1038/srep03515.


Host-associated microbiota varies in distribution depending on the body area inhabited. Gut microbes are known to interact with the human immune system, maintaining gut homoeostasis. Thus, we studied whether secreted-IgA (S-IgA) coat specific microbial taxa without inducing strong immune responses. To do so, we fractionated gut microbiota by flow cytometry. We found that active and S-IgA-coated bacterial fractions were characterized by a higher diversity than those observed in raw faecal suspensions. A long-tail effect was observed in family distribution, revealing that rare bacteria represent up to 20% of total diversity. While Firmicutes was the most abundant phylum, the majority of its sequences were not assigned at the genus level. Finally, the single-cell-based approach enabled us to focus on active and S-IgA-coated bacteria. Thus, we revealed a microbiota core common to the healthy volunteers participating in the study. Interestingly, this core was composed mainly of low frequency taxa (e.g. Sphingomonadaceae).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Bacteria / classification*
  • Bacteria / genetics
  • Bacteria / immunology*
  • Biodiversity
  • Computational Biology
  • DNA Barcoding, Taxonomic
  • Female
  • Gastrointestinal Tract / immunology*
  • Gastrointestinal Tract / microbiology*
  • Humans
  • Immunoglobulin A / immunology*
  • Male
  • Metagenome
  • Microbiota*
  • Sequence Analysis, DNA
  • Young Adult


  • Immunoglobulin A