A three-species anaerobic continuous-culture model community established to study trophic and electron-acceptor interactions relevant to subsurface anaerobic environments. Clostridium cellulolyticum ferments cellobiose, while Desulfovibrio vulgaris Hildenborough and Geobacter sulfurreducens depend on fermentation products and use sulfate and fumarate, respectively, as supplied electron acceptors.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Clostridium cellulolyticum — ontology label: Ruminiclostridium cellulolyticum | NCBITaxon:1521 · TaxonMech · TraitMech |
PRIMARY_DEGRADER
CROSS_FEEDER
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DOMINANT |
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| Desulfovibrio vulgaris Hildenborough — ontology label: Nitratidesulfovibrio vulgaris str. Hildenborough | NCBITaxon:882 · TaxonMech · TraitMech |
SYNTROPHIC_PARTNER
CROSS_FEEDER
|
COMMON |
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| Geobacter sulfurreducens | NCBITaxon:35554 · TaxonMech · TraitMech |
SYNTROPHIC_PARTNER
CROSS_FEEDER
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COMMON |
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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.
Cellobiose Fermentation Supports Partner Growth
CROSS_FEEDINGCellobiose fermentation by C. cellulolyticum supported the maintained three-species anaerobic chemostat community. Cellobiose depletion, acetate accumulation, sulfate consumption and fumarate reduction support trophic coupling. Individual metabolite allocations in the carbon/electron-flow model remain estimates, not independently traced interspecies fluxes; the exact hydrogen-versus-ethanol contribution to D. vulgaris was unresolved.
Source Taxon: Clostridium cellulolyticum
Metabolites: cellobiose (CHEBI:17057 · MediaIngredientMech · CMMMech)
Biological Processes:
- fermentation (GO:0006113 · PathwayMech)
C. cellulolyticum fermentation supplies carbon and reducing equivalents that support D. vulgaris growth with supplied sulfate. Maintained coculture and sulfate depletion support this dependence under the tested medium; hydrogen/ethanol partitioning is proposed rather than selectively measured, and reciprocal obligate dependence of the fermenter is not established.
Fermentation-derived substrates support G. sulfurreducens growth with supplied fumarate; measured acetate availability, fumarate depletion and succinate formation support the trophic interpretation. The allocation of acetate specifically to G. sulfurreducens is model-based rather than isotope-traced, so the arrow does not assert an independently measured donor-recipient flux.
Evidence
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doi:10.1186/1471-2180-10-149 - SUPPORT (IN_VITRO)"Cellobiose served as the carbon and energy source for C. cellulolyticum"
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doi:10.1186/1471-2180-10-149 - SUPPORT (IN_VITRO)"D. vulgaris and G. sulfurreducens derived carbon and energy from the metabolic products"
Sulfate-Linked Dependence of D. vulgaris
CROSS_FEEDINGD. vulgaris Hildenborough persisted using fermentation-derived nutrients with sulfate supplied as electron acceptor. Sulfate was depleted but remained available, supporting electron-donor limitation. Hydrogen and ethanol were proposed donors, but their relative transfer could not be distinguished by the measurements. This is supported trophic dependence under the tested medium, not proof of reciprocal obligate syntrophy with C. cellulolyticum.
Source Taxon: Clostridium cellulolyticum
Target Taxon: Desulfovibrio vulgaris Hildenborough
Metabolites: sulfate (CHEBI:16189 · MediaIngredientMech · CMMMech)
Biological Processes:
- sulfate reduction (GO:0019420 · PathwayMech)
Evidence
-
doi:10.1186/1471-2180-10-149 - SUPPORT (IN_VITRO)"D. vulgaris and G. sulfurreducens derived carbon and energy from the metabolic products"
-
doi:10.1186/1471-2180-10-149 - SUPPORT (IN_VITRO)"provided with sulfate and fumarate respectively as electron acceptors"
Fumarate-Linked Dependence of G. sulfurreducens
CROSS_FEEDINGG. sulfurreducens persisted with C. cellulolyticum fermentation products and supplied fumarate. Fumarate depletion, residual acetate and succinate production support fumarate-linked respiration and acceptor limitation. Acetate use and its species-specific allocation are interpreted through the metabolic model; the source does not directly trace every exchange or establish absolute exclusion of alternate interspecies routes.
Source Taxon: Clostridium cellulolyticum
Target Taxon: Geobacter sulfurreducens
Metabolites: fumarate (CHEBI:29806 · MediaIngredientMech · CMMMech)
Evidence
-
doi:10.1186/1471-2180-10-149 - SUPPORT (IN_VITRO)"D. vulgaris and G. sulfurreducens derived carbon and energy from the metabolic products"
-
doi:10.1186/1471-2180-10-149 - SUPPORT (IN_VITRO)"provided with sulfate and fumarate respectively as electron acceptors"
Electron Donor and Acceptor Limitation
Residual-substrate measurements and carbon/electron modeling indicated cellobiose limitation for C. cellulolyticum, electron-donor limitation for D. vulgaris and fumarate-acceptor limitation for G. sulfurreducens. This is an experimentally informed inference, not demonstrated ecological niche partitioning. Elevated-fumarate trials were associated with succinate accumulation and culture upset, but selective succinate causation was not isolated.
Metabolites: cellobiose (CHEBI:17057 · MediaIngredientMech · CMMMech), sulfate (CHEBI:16189 · MediaIngredientMech · CMMMech), fumarate (CHEBI:29806 · MediaIngredientMech · CMMMech)
Evidence
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doi:10.1186/1471-2180-10-149 - PARTIAL (COMPUTATIONAL)"growth of C. cellulolyticum and D. vulgaris were electron donor limited"
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doi:10.1186/1471-2180-10-149 - PARTIAL (COMPUTATIONAL)"G. sulfurreducens was electron acceptor limited"
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Which donor-recipient fluxes and limitation mechanisms can be resolved beyond the measured bulk substrates and model estimates?
The complete exact-system primary main text is now inspected, superseding the prior full-text-access limitation. It reports bulk cellobiose, acetate, fumarate/succinate and sulfate measurements, qPCR and microscopy supporting the maintained trophic community. Hydrogen and ethanol transfer could not be distinguished, and species-specific carbon/electron allocations were modeled. The later OptCom study of the same composition predicts a different hydrogen/ethanol allocation under biomass objectives and an assumed hydrogen recipient; those predictions are not new measured transfer. Elevated-fumarate upsets and possible succinate inhibition remain associated observations, not selective perturbation proof. No products from the separate two-species fuel-cell system are imported, and the modeled fourth-member extension is not part of this community.
Attaches to: ecological_interactions#Sulfate-Linked Dependence of D. vulgaris, ecological_interactions#Fumarate-Linked Dependence of G. sulfurreducens
1 evidence item(s)
D. vulgaris and G. sulfurreducens derived carbon and energy from the metabolic products
Supports trophic dependence; the now-inspected main text constrains the unresolved flux allocation rather than leaving all named products unknown.
External Resources
| Name | Repository | Resource ID |
|---|---|---|
|
Exact-system primary publication - ORNL anaerobic three-species model community
Primary open-access publication establishing the C. cellulolyticum, D. vulgaris Hildenborough, and G. sulfurreducens continuous-culture model community. |
OTHER | doi:10.1186/1471-2180-10-149 |
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Same-composition computational publication - OptCom model-community case study
Computational OptCom paper that includes a model-community case study for the same C. cellulolyticum, D. vulgaris Hildenborough, and G. sulfurreducens species composition. |
OTHER | PMID:22319433 |
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Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| Anaerobic continuous-culture operation | continuous culture | N/A |
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| Electron acceptor partitioning | sulfate supplied for D. vulgaris; fumarate supplied for G. sulfurreducens | N/A |
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| Subsurface anaerobic-environment model | trophic and electron-accepting interactions of subsurface anaerobic environments | N/A |
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Growth Media
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