A reciprocal cross-feeding coculture pairing N2-fixing Rhodopseudomonas palustris with fermentative Escherichia coli.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Rhodopseudomonas palustris | NCBITaxon:1076 · TaxonMech · TraitMech |
PRIMARY_PRODUCER
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N/A |
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| Escherichia coli | NCBITaxon:562 · TaxonMech · TraitMech |
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.
Ammonium Cross-Feeding By Nitrogen-Fixing R. palustris
CROSS_FEEDINGIn the tested anaerobic cocultures, nitrogen-fixing R. palustris supplies ammonium required by E. coli. Effective exchange depends on the donor and recipient context: engineered ammonium-excreting partners support growth, whereas WT-based emergence depends on recipient adaptation. This is not a claim that every wild-type pairing readily supports the same exchange.
Source Taxon: Rhodopseudomonas palustris
Target Taxon: Escherichia coli
Metabolites: dinitrogen (CHEBI:17997 · MediaIngredientMech · CMMMech), ammonium (CHEBI:28938 · MediaIngredientMech · CMMMech)
Biological Processes:
- nitrogen fixation (GO:0009399 · PathwayMech)
Ammonium transfer supports E. coli nitrogen acquisition and thereby its contribution to reciprocal coculture growth in the tested donor/recipient contexts; the rate and emergence of this exchange are strain dependent.
Evidence
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PMID:32788711 - SUPPORT (IN_VITRO)"R. palustris fixes dinitrogen gas (N2) via the enzyme nitrogenase and excretes ammonium (NH4+)"
E. coli Fermentation Product Cross-Feeding
CROSS_FEEDINGE. coli fermentation supplies acetate, lactate and succinate that R. palustris can use as carbon sources in the studied cocultures. The paper excludes formate from these consumed organic-acid carbon sources; ethanol excretion is not evidence that ethanol supplies the partner. This is the carbon-transfer half of the demonstrated reciprocal exchange.
Source Taxon: Escherichia coli
Target Taxon: Rhodopseudomonas palustris
Biological Processes:
- fermentation (GO:0006113 · PathwayMech)
The usable organic-acid products of E. coli fermentation supply carbon to R. palustris, enabling the carbon-transfer arm of the reciprocal carbon/nitrogen exchange; not every excreted fermentation product is a partner carbon source.
Evidence
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PMID:32788711 - SUPPORT (IN_VITRO)"The organic acids, with the exception of formate, serve as the sole carbon sources for R. palustris"
Reciprocal Carbon-Nitrogen Cross-Feeding
CROSS_FEEDINGReciprocal exchange of ammonium and usable organic-acid carbon supports the tested R. palustris-E. coli cocultures. Engineered donor contexts and adapted recipient contexts are distinct routes to coexistence, not a universal wild-type phenotype. Enhanced recipient uptake is the authors mechanistic interpretation of emergence; no new gene-design or feedback node is added here.
Metabolites: ammonium (CHEBI:28938 · MediaIngredientMech · CMMMech)
Biological Processes:
- nitrogen fixation (GO:0009399 · PathwayMech)
Evidence
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PMID:32788711 - SUPPORT (IN_VITRO)"Previously we engineered a cross-feeding coculture between N2-fixing Rhodopseudomonas palustris and fermentative Escherichia coli."
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PMID:32788711 - SUPPORT (IN_VITRO)"Engineered R. palustris excretes essential nitrogen as NH4+ to E. coli, while E. coli excretes essential carbon as fermentation products to R. palustris."
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN How general is reciprocal exchange across donor and recipient backgrounds?
The complete primary manuscript distinguishes engineered ammonium donors from WT-based emergence and shows that recipient adaptation can enable coculture growth without increased donor ammonium excretion. Retain both observed transfer directions, but do not generalize growth rates, readiness of exchange or inferred uptake feedback to arbitrary wild-type pairings. Species-level canonical taxonomy is unchanged. No new genetic design or experimental protocol is curated.
Attaches to: ecological_interactions#Ammonium Cross-Feeding By Nitrogen-Fixing R. palustris, ecological_interactions#E. coli Fermentation Product Cross-Feeding, ecological_interactions#Reciprocal Carbon-Nitrogen Cross-Feeding
1 evidence item(s)
multiple combinations of recipient and producer genotypes can lead to stable coexistence
Discussion limits coexistence to genotype/environment combinations, rather than all pairings.
Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| defined synthetic community design | Two-member coculture based on nitrogen transfer from R. palustris and carbon-rich fermentation product transfer from E. coli. | N/A |
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Growth Media
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