A staged two-member coculture for producing n-butanol from crystalline cellulose. The cellulolytic thermophile Clostridium thermocellum, represented in NCBI Taxonomy as Acetivibrio thermocellus ATCC 27405, first hydrolyzes Avicel cellulose. The butanol-producing Clostridium saccharoperbutylacetonicum strain N1-4 is then added for solvent production. The system is DOE-relevant because it couples consolidated cellulose deconstruction to cellulosic butanol production, a liquid biofuel and bioproduct target.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Clostridium thermocellum ATCC 27405 — ontology label: Acetivibrio thermocellus ATCC 27405 | NCBITaxon:203119 · TaxonMech · TraitMech |
PRIMARY_DEGRADER
CROSS_FEEDER
|
N/A |
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| Clostridium saccharoperbutylacetonicum N1-4 | NCBITaxon:1335640 · TaxonMech · TraitMech |
SECONDARY_FERMENTER
CROSS_FEEDER
|
N/A |
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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.
Staged Cellulose Hydrolysis Feeding Solventogenesis
CROSS_FEEDINGC. thermocellum preincubation on crystalline cellulose before N1-4 addition supports later butanol production, consistent with soluble-carbon cross-feeding. Cellulose is the feedstock and butanol the output, not the transfer currencies. PARTIAL - timing and temperature are coupled, and the N1-4 inoculum medium contains glucose; the intervention does not selectively quantify cellulose-derived transfer or explain solvent selectivity.
Source Taxon: Clostridium thermocellum ATCC 27405
Target Taxon: Clostridium saccharoperbutylacetonicum N1-4
Metabolites: cellulose (CHEBI:18246 · MediaIngredientMech · CMMMech), butanol (CHEBI:28885 · MediaIngredientMech · CMMMech)
Biological Processes:
- cellulose catabolic process (GO:0030245 · PathwayMech)
- fermentation (GO:0006113 · PathwayMech)
PARTIAL - preincubation supplies hydrolysis products that can support N1-4 solventogenesis. The staged-versus-simultaneous comparison supports this process contribution, while coupled temperature changes and glucose carried in with the inoculum prevent selective flux attribution or a complete explanation of low acetone.
Evidence
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PMID:21764954 - SUPPORT (IN_VITRO)"Butanol was produced from Avicel cellulose"
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PMID:21764954 - SUPPORT (IN_VITRO)"after it was incubated with C. thermocellum for at least 24 h"
Selective Butanol Production With Low Acetone
Butanol was the favored solvent in the reported coculture, with acetone undetectable in the 2011 experiment and very low in the 2013 abstract. The 2011 acetone-addition control argues against removal by C. thermocellum, while crude-extract assays retain acetone-pathway enzyme activities. These are community product and assay outcomes, not butanol donation or proof of pathway shutdown.
Participating Taxa: Clostridium thermocellum ATCC 27405, Clostridium saccharoperbutylacetonicum N1-4
Metabolites: butanol (CHEBI:28885 · MediaIngredientMech · CMMMech)
Biological Processes:
- fermentation (GO:0006113 · PathwayMech)
Evidence
-
PMID:21764954 - SUPPORT (IN_VITRO)"acetone was undetectable in this coculture system"
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PMID:22999358 - SUPPORT (IN_VITRO)"butanol was selectively produced with extremely low level of acetone"
Reduced Hydrogen Output and Proposed Redox Allocation
The 2013 abstract associates lower hydrogen output with higher butanol production and proposes future hydrogenase selection. The 2011 Discussion proposes redox allocation. PARTIAL - neither the available abstract nor the 2011 coculture assays establish selective hydrogenase causality or interspecies hydrogen donation.
Participating Taxa: Clostridium thermocellum ATCC 27405, Clostridium saccharoperbutylacetonicum N1-4
Metabolites: hydrogen (CHEBI:18276 · MediaIngredientMech · CMMMech), butanol (CHEBI:28885 · MediaIngredientMech · CMMMech)
Biological Processes:
- fermentation (GO:0006113 · PathwayMech)
HYPOTHESIZED - reduced electron allocation to hydrogen could favor the butanol branch and contribute to solvent selectivity. The observed inverse association supports this redox proposal, not a selectively demonstrated causal effect or transfer of hydrogen between partners.
Evidence
-
PMID:22999358 - PARTIAL (IN_VITRO)"hydrogen production decreased and butanol was selectively produced"
-
PMID:22999358 - PARTIAL (IN_VITRO)"high butanol production correlates with low hydrogen production"
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Which carbon-transfer and redox mechanisms determine the staged coculture solvent profile?
Staging, temperature and partner comparisons support the process; acetone-addition and crude-enzyme controls constrain alternative explanations. Carbon tracing with inoculum carryover controls and selective redox perturbations would resolve causal contributions. The 2013 follow-up was available only as an abstract, so its correlation must not be promoted to demonstrated hydrogen transfer or hydrogenase causality.
Attaches to: ecological_interactions#Staged Cellulose Hydrolysis Feeding Solventogenesis, ecological_interactions#Selective Butanol Production With Low Acetone, ecological_interactions#Reduced Hydrogen Output and Proposed Redox Allocation
External Resources
| Name | Repository | Resource ID |
|---|---|---|
|
Exact-system primary publication - crystalline cellulose to butanol coculture
Primary publication reporting C. thermocellum and C. saccharoperbutylacetonicum N1-4 coculture production of butanol from crystalline cellulose. |
OTHER | PMID:21764954 |
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Open full text for primary crystalline cellulose study
Open-access full text for the primary C. thermocellum/N1-4 cellulose-to-butanol study. |
OTHER | PMCID:PMC3187149 |
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Exact-species follow-up publication - hydrogen and butanol selectivity
Follow-up exact-species coculture publication linking decreased hydrogen production with selective butanol production and very low acetone. |
OTHER | PMID:22999358 |
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Same-species lignocellulose extension - alkali-pretreated rice straw
Later same-species-pair coculture study using C. thermocellum NBRC 103400 and C. saccharoperbutylacetonicum N1-4 on delignified rice straw. |
OTHER | PMID:25818258 |
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Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| Crystalline cellulose substrate | 4% Avicel cellulose | N/A |
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| Thermocellum preincubation | at least 24 h before N1-4 addition | N/A |
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| Butanol titer on Avicel | 7.9 g/liter after 9 days | N/A |
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| Delignified rice straw extension | 5.5 to 6.9 g/L butanol from 40 g/L delignified rice straw | N/A |
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