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Microbiome

How much do gut bacterial gene contents differ?

Zhu A, Sunagawa S, Mende DR, et al. · Genome biology · 2015

Open access · cc by · source: Europe PMC

Same gut bacterial species can differ widely in gene content across people, shaping functional individuality.

Study at a glance

Design
Cross-sectional — Metagenomic gene-deletion detection quantifying within-species gene content across gut communities
N
N=207 · 252 fecal metagenomes from 207 individuals (HMP and European MetaHIT)
Population
Human gut metagenomes from public cohorts
Outcome
Inter-individual within-species gene-content variation

Structured fields used in claim comparison tables when every cited study has a complete layer.

Key findings

Strain-level gene content varies substantially among individuals for the same species in natural habitats.

Methodology

Developed metagenomic gene-deletion detection and quantified within-species gene-content differences in human gut communities.

Limitations

Presence/absence is not full phenotype; sample sizes remain limited.

How this study connects

Role on claims

Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.

  • QualifiesMicrobiomeconcept

    Bacterial bile-salt enzymes can change host bile acids and weight-related phenotypes in models.

    Selective bacterial bile-salt hydrolases can change host bile-acid chemistry and weight-related phenotypes in colonization models—evidence that specific microbial enzymes, not only community membership lists, can matter for host physiology.

    Scope note — different question — strain gene-content variation across people

    Limits the claim's scope: a different population, assay, or outcome.

  • SupportsMicrobiomeconcept

    Strain-level gene content varies a lot within the same gut species — species labels are coarse.

    Even within the same named gut species, strain-level gene content varies substantially among healthy people—so species labels alone understate functional diversity.

    Evidence for the claim as stated.

  • A gene-deletion detection method on human gut metagenomes found that strain-level gene content for the same species varies substantially among individuals in natural habitats. Presence/absence is not a full phenotype, and sample sizes remain limited.

    Evidence for the claim as stated.

  • Shotgun gene-content metagenomics (within-species deletions across people; infant diet genes plus 459/660 host transcripts; B. dorei before seroconversion) is not the same experiment as HMP-style 16S biogeography (>24 million reads, 2,983 specimens, ~8,167 V3–V5 reads). A 16S habitat map cannot report accessory genes; a gene-deletion call cannot replace body-wide taxonomy.

    Evidence for the claim as stated.

  • Even among shotgun studies, claims differ in strength. Infant diet work is n=6 versus 6 with host-transcript correlations; DIPP is 76 children and 947 samples but still does not prove B. dorei causes autoimmunity; within-species gene content varies without assigning a disease. Pooling them as 'the microbiome causes immunity' overreads every design.

    Evidence for the claim as stated.

Open questions

Tensions this paper is part of

From concept pages' “where studies disagree.” Disagreement means the same question; scope means different assays, populations, or outcomes.

  • Scope difference — different assays, populations, or outcomes

    Shotgun gene-content metagenomics (within-species deletions across people; infant diet genes plus 459/660 host transcripts; B. dorei before seroconversion) is not the same experiment as HMP-style 16S biogeography (>24 million reads, 2,983 specimens, ~8,167 V3–V5 reads). A 16S habitat map cannot report accessory genes; a gene-deletion call cannot replace body-wide taxonomy.

  • Scope difference — different assays, populations, or outcomes

    Even among shotgun studies, claims differ in strength. Infant diet work is n=6 versus 6 with host-transcript correlations; DIPP is 76 children and 947 samples but still does not prove B. dorei causes autoimmunity; within-species gene content varies without assigning a disease. Pooling them as 'the microbiome causes immunity' overreads every design.

History

When this study was placed

Dated entries from the concept change log — when this paper was added or removed as support, challenge, or qualifier on a claim.

  1. 2026-09-14

    Removed as supporting evidence on Microbiome

    Selective bacterial bile-salt hydrolases can change host bile-acid chemistry and weight-related phenotypes in colonization models—evidence that specific microbial enzymes, not only community membership lists, can matter for host physiology.

  2. 2026-09-14

    Placed as a scope qualifier on Microbiome

    Selective bacterial bile-salt hydrolases can change host bile-acid chemistry and weight-related phenotypes in colonization models—evidence that specific microbial enzymes, not only community membership lists, can matter for host physiology.

  3. 2026-09-14

    Placed as supporting evidence on Microbiome

    Even within the same named gut species, strain-level gene content varies substantially among healthy people—so species labels alone understate functional diversity.

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Same topic cluster — not a recommendation engine.