A defined binary microbial fuel cell coculture pairing the cellulolytic fermenter Clostridium cellulolyticum with the electrochemically active bacterium Geobacter sulfurreducens. The community couples cellulose hydrolysis and fermentation to anode respiration: C. cellulolyticum metabolizes cellulose, while G. sulfurreducens uses fermentation products to transfer electrons to the anode. The same exact two-species composition was reported in an initial cellulose-to-electricity study and a follow-up cellulose-fed microbial biofilm ecology study. The system is relevant to DOE bioenergy because it converts cellulosic biomass into electricity in a controlled bioelectrochemical reactor.
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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ABUNDANT |
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| Geobacter sulfurreducens | NCBITaxon:35554 · TaxonMech · TraitMech |
CROSS_FEEDER
SYNTROPHIC_PARTNER
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ABUNDANT |
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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.
Cellulose Fermentation Feeding Electrode Respiration
CROSS_FEEDINGC. cellulolyticum fermentation supplies products that support G. sulfurreducens anode respiration in the defined cellulose-fed MFC. Binary current production and the negative pure-culture controls support functional complementarity. The primary abstract calls this syntrophy, but does not demonstrate obligate growth dependence or isolate product removal as the mechanism favoring the fermenter. Hydrogen, acetate and ethanol were reported as residual metabolites; that list does not establish uptake of every compound, especially ethanol, by Geobacter or quantify partner-specific transfer.
Source Taxon: Clostridium cellulolyticum
Target Taxon: Geobacter sulfurreducens
Metabolites: cellulose (CHEBI:18246 · MediaIngredientMech · CMMMech), acetate (CHEBI:30089 · MediaIngredientMech · CMMMech), dihydrogen (CHEBI:18276 · MediaIngredientMech · CMMMech), ethanol (CHEBI:16236 · MediaIngredientMech · CMMMech)
Biological Processes:
- cellulose catabolic process (GO:0030245 · PathwayMech)
- fermentation (GO:0006113 · PathwayMech)
Fermentative conversion of cellulose supplies electron-donor products for G. sulfurreducens anode respiration, enabling current from substrates on which neither pure culture produced electricity. The conversion is supported by the binary-versus-pure-culture comparison; the accessible abstract does not resolve each metabolite contribution or transfer rate.
Evidence
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PMID:17695929 - SUPPORT (IN_VITRO)"requires a syntrophic microbial community"
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PMID:17695929 - PARTIAL (IN_VITRO)"Hydrogen, acetate, and ethanol were the main residual metabolites"
Defined Binary Electricity Production
The binary coculture produced current from CMC and MN301 cellulose, whereas neither pure culture did so. CMC degradation increased from 42% in C. cellulolyticum monoculture to 64% in coculture. These measured conversion and substrate-degradation outcomes support division of labor, but do not by themselves establish reciprocal fitness benefits or a unique metabolite-removal mechanism.
Source Taxon: Clostridium cellulolyticum
Target Taxon: Geobacter sulfurreducens
Metabolites: cellulose (CHEBI:18246 · MediaIngredientMech · CMMMech), acetate (CHEBI:30089 · MediaIngredientMech · CMMMech)
Biological Processes:
- cellulose catabolic process (GO:0030245 · PathwayMech)
Evidence
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PMID:17695929 - SUPPORT (IN_VITRO)"Neither pure culture alone produced electricity"
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PMID:17695929 - SUPPORT (IN_VITRO)"increased CMC degradation from 42% to 64%"
Observed Substrate-Dependent Spatial Distribution
FISH and qPCR showed that most C. cellulolyticum cells were associated with suspended MN301 cellulose particles and most G. sulfurreducens cells with the electrode. With soluble CMC, both organisms occurred in suspension and biofilm samples. This is substrate-dependent spatial distribution, not a demonstrated requirement that physical separation causes or improves electricity generation, nor an isolated resource-partitioning mechanism.
Source Taxon: Clostridium cellulolyticum
Target Taxon: Geobacter sulfurreducens
Metabolites: cellulose (CHEBI:18246 · MediaIngredientMech · CMMMech)
Evidence
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PMID:18725730 - SUPPORT (IN_VITRO)"particulate MN301 cellulose was used as sole substrate"
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PMID:18725730 - SUPPORT (IN_VITRO)"most Clostridium cells were found adhered to cellulose particles"
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PMID:18725730 - SUPPORT (IN_VITRO)"most Geobacter cells were attached to the electrode"
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PMID:18725730 - SUPPORT (IN_VITRO)"both bacteria resided in suspension and biofilm samples"
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Which exchanged products and spatial arrangements causally control current and partner fitness?
PMIDs:17695929 and 18725730 were reviewed through fresh primary abstracts and cached snippets; full bodies were not obtained through the attempted public DOI/search routes. Residual metabolites do not measure individual uptake, and FISH/qPCR localization does not establish its causal benefit. Partner-resolved metabolite flux, spatial perturbations and growth measurements are needed to separate these mechanisms. Preserve binary current and increased CMC degradation as measured endpoints.
Attaches to: ecological_interactions#Cellulose Fermentation Feeding Electrode Respiration, ecological_interactions#Defined Binary Electricity Production, ecological_interactions#Observed Substrate-Dependent Spatial Distribution
External Resources
| Name | Repository | Resource ID |
|---|---|---|
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Exact-system primary publication - cellulose-to-electricity binary MFC coculture
Primary publication reporting electricity production from cellulose by the exact C. cellulolyticum and G. sulfurreducens two-species coculture. |
OTHER | PMID:17695929 |
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Exact-system follow-up publication - cellulose-fed microbial ecology and biofilm localization
Follow-up publication reporting microbial ecology, FISH, and qPCR observations for the same C. cellulolyticum and G. sulfurreducens cellulose-fed MFC coculture. |
OTHER | PMID:18725730 |
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Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| Cellulose substrate | carboxymethyl cellulose or MN301 cellulose | N/A |
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| Anode as extracellular electron acceptor | microbial fuel cell anode | N/A |
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Growth Media
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