Defined two-strain anaerobic gut coculture containing Bifidobacterium bifidum JCM1254 and Faecalibacterium prausnitzii A2-165 (JCM31915). The strains were grown in 48-well batch cultures of sugar- and volatile-fatty-acid-free YCFA broth supplied with 0.5% total carbohydrate as 2′-fucosyllactose, fructooligosaccharides, or mixtures of the two. Monocultures showed B. bifidum responding to 2′-FL-rich substrates and F. prausnitzii growing in FOS-containing conditions; in the two-member coculture, total OD600 and lactate/acetate accumulation increased under 2′-FL-rich conditions, but butyrate peaked specifically at 10% 2′-FL plus 90% FOS, indicating ratio-dependent substrate complementarity and metabolite-mediated interaction.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Bifidobacterium bifidum JCM1254 — ontology label: Bifidobacterium bifidum | NCBITaxon:1681 · TaxonMech · TraitMech |
PRIMARY_DEGRADER
CROSS_FEEDER
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N/A |
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| Faecalibacterium prausnitzii A2-165 — ontology label: Faecalibacterium prausnitzii | NCBITaxon:853 · TaxonMech · TraitMech |
PRIMARY_DEGRADER
CROSS_FEEDER
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N/A |
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Ecological Interactions
The graph shows only explicitly linked interaction participants. Community members without an asserted participant link are omitted; membership alone does not imply an interaction.
2′-FL/FOS ratio-dependent butyrate peak
Mixed 2′-FL/FOS substrates uncoupled total co-culture growth from butyrate production: OD600 and lactate/acetate were highest under 2′-FL-rich conditions, whereas butyrate was maximal at 10% 2′-FL plus 90% FOS. The authors interpreted that nonlinear optimum as a balance between FOS-supported F. prausnitzii abundance and metabolites supplied by active B. bifidum. This was a 24-hour endpoint at fixed 0.5% carbohydrate, not a general in-vivo optimum or donor-resolved transfer measurement.
Participating Taxa: Bifidobacterium bifidum JCM1254, Faecalibacterium prausnitzii A2-165
Metabolites: 2′-fucosyllactose (CHEBI:147155 · MediaIngredientMech · CMMMech), acetate (CHEBI:30089 · MediaIngredientMech · CMMMech), butyrate (CHEBI:17968 · MediaIngredientMech · CMMMech)
Biological Processes:
- carbohydrate fermentation (GO:0005975 · PathwayMech)
Evidence
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PMID:42655156 - SUPPORT (IN_VITRO)"butyrate production was highest at 10% 2′-FL and 90% FOS"
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PMID:42655156 - SUPPORT (IN_VITRO)"conditions that maximized total co-culture growth did not necessarily maximize butyrate production"
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PMID:42655156 - PARTIAL (IN_VITRO)"this study showed that the mixing ratio of 2′-FL and FOS could nonlinearly regulate butyrate production through substrate complementarity and metabolite-mediated interactions between B. bifidum and F. prausnitzii"
Putative B. bifidum metabolite support of F. prausnitzii butyrate output
CROSS_FEEDINGPARTIAL - B. bifidum monocultures accumulated acetate/lactate but no detectable butyrate; the mixed culture showed the 10:90 substrate-ratio butyrate peak. The authors infer that B. bifidum-derived acetate or other products contribute to F. prausnitzii butyrate formation. Relative qPCR and estimated genome-copy changes are distinct from viable-cell counts; neither establishes donor-resolved flux. The pairwise metabolite annotation remains acetate only.
Source Taxon: Bifidobacterium bifidum JCM1254
Target Taxon: Faecalibacterium prausnitzii A2-165
Metabolites: acetate (CHEBI:30089 · MediaIngredientMech · CMMMech)
Biological Processes:
- carbohydrate fermentation (GO:0005975 · PathwayMech)
Evidence
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PMID:42655156 - SUPPORT (IN_VITRO)"In contrast, butyrate production was not detected under any of the tested conditions"
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PMID:42655156 - SUPPORT (IN_VITRO)"butyrate production was highest at 10% 2′-FL and 90% FOS"
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PMID:42655156 - PARTIAL (IN_VITRO)"acetate and possibly other fermentation products derived from B. bifidum may have contributed to butyrate formation by F. prausnitzii"
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Does B. bifidum-derived acetate directly enter F. prausnitzii butyrate, and how much of the 10:90 2′-FL/FOS butyrate peak is controlled by pH or residual substrate depletion?
The paper measured only a 24 h endpoint, did not measure or control culture pH, did not quantify residual 2′-FL or FOS, and did not trace metabolic flux. Those source limitations leave the exact acetate-transfer contribution and pH/substrate constraints unresolved even though butyrate peaked in the 10:90 2′-FL/FOS co-culture.
Attaches to: ecological_interactions#Putative B. bifidum metabolite support of F. prausnitzii butyrate output, environmental_factors#2′-FL/FOS substrate ratio
3 evidence item(s)
the culture pH was neither measured nor controlled
Names the unresolved pH constraint.
residual 2′-FL and FOS concentrations after 24 h were not quantified
Names the unresolved substrate-depletion constraint.
the metabolic flux was not directly measured in this study
Names the direct-flux measurement gap for the inferred cross-feeding step.
External Resources
| Name | Repository | Resource ID |
|---|---|---|
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Primary publication for the 2′-FL/FOS butyrate coculture
PubMed record for Iguchi et al. 2026 Microorganisms article on 2′-FL/FOS ratio-dependent B. bifidum / F. prausnitzii butyrate production. |
OTHER | PMID:42655156 |
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DOI landing page
DOI link to the Microorganisms article. |
OTHER | doi:10.3390/microorganisms14081812 |
Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| 2′-FL/FOS substrate ratio | 0:100 to 100:0 | % w/w within 0.5% w/v total carbohydrate |
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| Anaerobic 37 °C batch incubation | 37 | °C |
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Growth Media
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