A defined anaerobic synthetic coculture that combines the acetogenic syngas fermenter Clostridium ljungdahlii with the chain-elongating bacterium Clostridium kluyveri in a continuously fed syngas bioprocess with in-line product extraction. C. ljungdahlii converts syngas into ethanol and acetate, while C. kluyveri uses ethanol for reverse-beta-oxidation chain elongation to butyrate and caproate. The same community also produced longer-chain alcohols including butanol, hexanol, and traces of octanol within a narrow pH range. The system is relevant to DOE carbon utilization and renewable fuels because it converts C1 gases into C4-C8 fuels and chemicals through microbial cross-feeding.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Clostridium ljungdahlii | NCBITaxon:1538 |
PRIMARY_PRODUCER
CROSS_FEEDER
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ABUNDANT |
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| Clostridium kluyveri | NCBITaxon:1534 |
CROSS_FEEDER
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ABUNDANT |
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Ecological Interactions
Syngas Fermentation to Ethanol and Acetate
CROSS_FEEDINGSource Taxon: Clostridium ljungdahlii
Target Taxon: Clostridium kluyveri
Metabolites: carbon monoxide (CHEBI:17245), carbon dioxide (CHEBI:16526), hydrogen (CHEBI:18276), acetate (CHEBI:30089), ethanol (CHEBI:16236)
Biological Processes:
- fermentation (GO:0006113)
Evidence
-
PMID:27877166 - SUPPORT (IN_VITRO)"syngas-fermentation process with Clostridium ljungdahlii and Clostridium kluyveri"
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PMID:27877166 - SUPPORT (IN_VITRO)"ethanol and acetate"
Ethanol-Driven Chain Elongation
CROSS_FEEDINGSource Taxon: Clostridium kluyveri
Target Taxon: Clostridium ljungdahlii
Metabolites: ethanol (CHEBI:16236), acetate (CHEBI:30089), butyrate (CHEBI:30772), hexanoate (CHEBI:30776)
Biological Processes:
- fermentation (GO:0006113)
Evidence
-
PMID:27877166 - SUPPORT (IN_VITRO)"utilized by C. kluyveri to chain elongate"
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PMID:27877166 - SUPPORT (IN_VITRO)"resulting in n-butyrate and n-caproate"
Biological Reduction to Longer-Chain Alcohols
CROSS_FEEDINGSource Taxon: Clostridium ljungdahlii
Target Taxon: Clostridium kluyveri
Metabolites: butyrate (CHEBI:30772), hexanoate (CHEBI:30776), butanol (CHEBI:28885)
Biological Processes:
- fermentation (GO:0006113)
Evidence
-
PMID:27877166 - SUPPORT (IN_VITRO)"likely reduced the produced carboxylates to their corresponding alcohols"
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PMID:27877166 - SUPPORT (IN_VITRO)"longer-chain alcohols n-butanol, n-hexanol, and n-octanol"
pH-Restricted Product Formation
COMPETITIONSource Taxon: Clostridium ljungdahlii
Target Taxon: Clostridium kluyveri
Metabolites: acetate (CHEBI:30089), ethanol (CHEBI:16236)
Biological Processes:
- fermentation (GO:0006113)
Evidence
-
PMID:27877166 - SUPPORT (IN_VITRO)"narrow pH spectrum of 5.7-6.4"
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PMID:27877166 - SUPPORT (IN_VITRO)"two bioprocesses compete for intermediates"
External Resources
| Name | Repository | Resource ID |
|---|---|---|
|
Exact-system primary publication - continuous syngas alcohol coculture
Primary open-access study of continuous syngas conversion by C. ljungdahlii and C. kluyveri with in-line product extraction. |
OTHER | PMID:27877166 |
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DOI landing page - Frontiers in Microbiology article
DOI landing page for the primary exact-composition coculture article. |
OTHER | doi:10.3389/fmicb.2016.01773 |
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Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| Syngas feed | 60% CO, 35% H2, and 5% CO2 | N/A |
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| pH window | pH 5.7-6.4 | N/A |
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| Product extraction | gas stripping and product condensing | N/A |
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