A defined anaerobic synthetic coculture combining the acetogenic syngas fermenter Clostridium autoethanogenum with the chain-elongating bacterium Clostridium kluyveri. C. autoethanogenum converts carbon monoxide or syngas into acetate and ethanol, while C. kluyveri consumes these products for chain elongation, producing C4 and C6 fatty acids and higher alcohols. The system is relevant to DOE carbon utilization and renewable fuels because it couples gas fermentation with microbial upgrading of CO/syngas-derived intermediates in one growth vessel.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Clostridium autoethanogenum | NCBITaxon:84023 · TaxonMech · TraitMech |
PRIMARY_PRODUCER
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ABUNDANT |
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| Clostridium kluyveri | NCBITaxon:1534 · TaxonMech · TraitMech |
CROSS_FEEDER
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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.
Acetogenic CO and Syngas Fermentation
CROSS_FEEDINGC. autoethanogenum converts CO or syngas to acetate and ethanol that support C. kluyveri chain elongation. Product profiles and pure-culture comparisons support this cross-feeding model. In the 2019 chemostat study, partner ethanol production and electron allocation in coculture were reverse-calculated from measured chain-elongated products and assumed stoichiometry, not directly measured partner-specific fluxes.
Source Taxon: Clostridium autoethanogenum
Target Taxon: Clostridium kluyveri
Metabolites: carbon monoxide (CHEBI:17245 · MediaIngredientMech · CMMMech), carbon dioxide (CHEBI:16526 · MediaIngredientMech · CMMMech), acetate (CHEBI:30089 · MediaIngredientMech · CMMMech), ethanol (CHEBI:16236 · MediaIngredientMech · CMMMech)
Biological Processes:
- fermentation (GO:0006113 · PathwayMech)
C. autoethanogenum supplies ethanol and acetate that C. kluyveri consumes for chain elongation to C4 and C6 products.
Evidence
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PMID:27042211 - SUPPORT (IN_VITRO)"Acetate and ethanol are main products"
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PMID:31792266 - SUPPORT (IN_VITRO)"converted CO to acetate and traces of ethanol"
Ethanol-Driven Chain Elongation
CROSS_FEEDINGC. kluyveri uses ethanol and acetate for chain elongation to butyrate and caproate, which can supply C. autoethanogenum for reduction to butanol and hexanol. The 2016 study demonstrated acid formation by C. kluyveri and higher-alcohol formation by acid-supplemented C. autoethanogenum pure cultures. Higher alcohols are therefore coculture products, not products assigned to C. kluyveri alone; this attribution is bounded to the tested conditions.
Source Taxon: Clostridium kluyveri
Target Taxon: Clostridium autoethanogenum
Metabolites: acetate (CHEBI:30089 · MediaIngredientMech · CMMMech), ethanol (CHEBI:16236 · MediaIngredientMech · CMMMech), butyrate (CHEBI:17968 · MediaIngredientMech · CMMMech)
Biological Processes:
- fermentation (GO:0006113 · PathwayMech)
Evidence
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PMID:27042211 - SUPPORT (IN_VITRO)"converting CO and syngas to a mixture"
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PMID:27042211 - SUPPORT (IN_VITRO)"butyrate and caproate"
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PMID:27042211 - SUPPORT (IN_VITRO)"Butanol and hexanol were produced"
Proposed thermodynamic ethanol pull by C. kluyveri
HYPOTHESIZED - ethanol consumption by C. kluyveri lowers its extracellular concentration and thermodynamically favors further ethanol formation by C. autoethanogenum. Chemostat products, reverse-calculated ethanol flux, hydrogen and acetate additions, and the absence of a major uniform central-metabolism transcript response support this interpretation. They do not exclude protein abundance or post-translational regulation. This node represents a proposed feedback effect of product removal, not ethanol donation from C. kluyveri to the acetogen.
Source Taxon: Clostridium kluyveri
Target Taxon: Clostridium autoethanogenum
Metabolites: ethanol (CHEBI:16236 · MediaIngredientMech · CMMMech)
Biological Processes:
- fermentation (GO:0006113 · PathwayMech)
HYPOTHESIZED - C. kluyveri consumption keeps ethanol low and could favor C. autoethanogenum solventogenesis, supplying further ethanol for chain elongation. Stoichiometric flux estimates and perturbations support this feedback model, but do not uniquely establish thermodynamics as its mediator.
Evidence
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PMID:31792266 - PARTIAL (IN_VITRO)"shifted its metabolism significantly towards solventogenesis"
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PMID:31792266 - PARTIAL (IN_VITRO)"continuous removal of ethanol by C. kluyveri"
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PMID:31792266 - PARTIAL (IN_VITRO)"protein levels or post-translational modifications cannot be ruled out"
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Does ethanol removal directly mediate the solventogenic shift independently of protein-level regulation?
PMID:31792266 combines measured product pools, stoichiometric reverse-calculation, transcriptomics and hydrogen/acetate perturbations. The thermodynamic explanation is supported but not exclusive. Selective ethanol-removal perturbations with partner-resolved flux and protein-level measurements would distinguish it from alternative regulation. PMID:33240469 remains computational support, not a new experimentally demonstrated interaction.
Attaches to: ecological_interactions#Acetogenic CO and Syngas Fermentation, ecological_interactions#Ethanol-Driven Chain Elongation, ecological_interactions#Proposed thermodynamic ethanol pull by C. kluyveri
External Resources
| Name | Repository | Resource ID |
|---|---|---|
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Exact-system primary publication - CO/syngas chain elongation coculture
Primary publication establishing the C. autoethanogenum and C. kluyveri synthetic coculture for C4/C6 fatty acid and higher alcohol production from CO or syngas. |
OTHER | PMID:27042211 |
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Exact-system publication - metabolic interaction and solventogenic shift
Follow-up exact species-pair publication analyzing microbial interactions and the co-cultivation-induced metabolic shift during CO conversion. |
OTHER | PMID:31792266 |
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Exact-system publication - genome-scale community model
Genome-scale constraint-based model of the C. autoethanogenum and C. kluyveri coculture on syngas for medium-chain fatty acid production. |
OTHER | PMID:33240469 |
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Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| Gas substrate | carbon monoxide or syngas | N/A |
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| Acetate supplementation | acetate stimulated production rates | N/A |
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| pH | pH influences growth and caproate toxicity | N/A |
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Growth Media
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