A defined anaerobic artificial symbiosis pairing the cellulolytic, butyrate-producing mesophile Clostridium cellulovorans 743B with the non-cellulolytic solventogenic bacterium Clostridium beijerinckii NCIMB 8052. The coculture was designed for consolidated bioprocessing of alkali extracted deshelled corn cobs, where C. cellulovorans saccharifies lignocellulose and produces butyric acid, and C. beijerinckii converts the released soluble sugars and butyric acid into acetone-butanol-ethanol solvents. The system is DOE-relevant as a lignocellulosic biomass-to-biofuel community model using an agricultural residue feedstock.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Clostridium cellulovorans 743B | NCBITaxon:573061 · TaxonMech · TraitMech |
PRIMARY_DEGRADER
CROSS_FEEDER
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ABUNDANT |
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| Clostridium beijerinckii NCIMB 8052 — ontology label: Clostridium beijerinckii | NCBITaxon:1520 · TaxonMech · TraitMech |
SECONDARY_FERMENTER
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.
Lignocellulose Saccharification Feeding Solventogenesis
CROSS_FEEDINGC. cellulovorans 743B saccharifies AECC and supplies soluble sugars for C. beijerinckii NCIMB 8052 solventogenesis. The primary study compares monocultures and coculture, measures sugar accumulation and depletion, and reports ABE output. Cellulose is the polymer substrate and ABE compounds are products, not molecules all transferred between partners. Inoculation timing, ratio and pH-control duration also affect performance; product supply alone does not establish the cause of the population dynamics.
Source Taxon: Clostridium cellulovorans 743B
Target Taxon: Clostridium beijerinckii NCIMB 8052
Metabolites: cellulose (CHEBI:18246 · MediaIngredientMech · CMMMech), ethanol (CHEBI:16236 · MediaIngredientMech · CMMMech), butanol (CHEBI:28885 · MediaIngredientMech · CMMMech), acetone (CHEBI:15347 · MediaIngredientMech · CMMMech)
Biological Processes:
- cellulose catabolic process (GO:0030245 · PathwayMech)
- fermentation (GO:0006113 · PathwayMech)
Evidence
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PMID:25023325 - SUPPORT (IN_VITRO)"soluble sugars and butyric acid generated can be subsequently utilized by Clostridium beijerinckii NCIMB 8052"
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PMID:25023325 - SUPPORT (IN_VITRO)"produce solvents by consolidated bioprocessing (CBP) with alkali extracted deshelled corn cobs (AECC)"
Butyric Acid Support of Butanol Production
CROSS_FEEDINGPARTIAL - C. cellulovorans produces butyric acid in monoculture, and the coculture produces butanol without external butyric-acid addition. Acid accumulation followed by reassimilation during solventogenesis supports an in-situ cosubstrate contribution to C. beijerinckii. The primary study also changes pH control and inoculation conditions. It does not trace the partner origin of every acid molecule or isolate butyrate necessity from these covariates, and does not establish that butyrate causes upstream AECC saccharification.
Source Taxon: Clostridium cellulovorans 743B
Target Taxon: Clostridium beijerinckii NCIMB 8052
Metabolites: butyric acid (CHEBI:30772 · MediaIngredientMech · CMMMech), butanol (CHEBI:28885 · MediaIngredientMech · CMMMech)
Biological Processes:
- fermentation (GO:0006113 · PathwayMech)
Evidence
-
PMID:25023325 - PARTIAL (IN_VITRO)"produce butyric acid, instead of adding cellulase and butyric acid to the medium"
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PMID:25023325 - PARTIAL (IN_VITRO)"soluble sugars and butyric acid generated can be subsequently utilized"
Population Dynamics and Proposed Competition
PARTIAL - the reported 16S-based abundance assay showed changing partner proportions during coculture, with early C. cellulovorans dominance and later C. beijerinckii dominance. The authors interpret stage-dependent cooperation and competition in relation to pH and nutrient availability, but explicitly leave the molecular mechanism unresolved. Methods describe RNA extraction and cDNA for this assay, so the reported proportions are not direct cell counts. The experiments vary inoculation and pH conditions; abundance changes alone do not isolate reciprocal resource competition or its molecular mediator.
Biological Processes:
- interspecies interaction between organisms (GO:0044419 · PathwayMech)
Evidence
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PMID:25023325 - PARTIAL (IN_VITRO)"mechanisms of cooperation and competition between the two strains during the co-culture process"
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PMID:25023325 - SUPPORT (IN_VITRO)"real-time PCR assay based on the 16S rRNA gene sequence was performed"
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN How much of solventogenesis and partner dynamics is mediated by acid transfer, pH and resource competition?
PMID:25023325 supports sugar supply, in-situ acid formation and measured solvent production, and experimentally compares inoculation timing, ratio and pH-control duration. The full primary Results/Discussion leave molecular competition/cooperation unresolved. RNA/cDNA-based 16S proportions are not direct cell counts. Partner-resolved flux, selective acid perturbations with matched pH, and independent population quantification would distinguish these contributions. Butyrate provision does not itself establish a causal arrow to upstream saccharification.
Attaches to: ecological_interactions#Lignocellulose Saccharification Feeding Solventogenesis, ecological_interactions#Butyric Acid Support of Butanol Production, ecological_interactions#Population Dynamics and Proposed Competition
External Resources
| Name | Repository | Resource ID |
|---|---|---|
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Exact-system primary publication - AECC to ABE artificial symbiosis
Primary publication reporting AECC degradation and ABE solvent production by the C. cellulovorans 743B and C. beijerinckii NCIMB 8052 coculture. |
OTHER | PMID:25023325 |
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Open full text - AECC to ABE artificial symbiosis
Open-access full text for the Microbial Cell Factories study of the C. cellulovorans 743B and C. beijerinckii NCIMB 8052 coculture. |
OTHER | PMCID:PMC4223388 |
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Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| Alkali extracted deshelled corn cobs | sole carbon source | N/A |
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| Optimized AECC degradation | 68.6 g/L AECC degraded | N/A |
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| Solvent production | 11.8 g/L total solvents in less than 80 h | N/A |
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Growth Media
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