A defined anaerobic cellulose-to-hydrogen coculture pairing cellulolytic Cellulomonas sp. strain ATCC 21399 with the purple nonsulfur phototroph Rhodopseudomonas capsulata, now classified as Rhodobacter capsulatus. The Cellulomonas partner ferments cellulose to organic acids, while R. capsulata grows photoheterotrophically on those products and evolves molecular hydrogen through nitrogenase. The system is DOE-relevant as an early model for lignocellulosic biohydrogen production by division of labor between cellulose fermentation and phototrophic hydrogen evolution.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Cellulomonas sp. strain ATCC 21399 — ontology label: Cellulomonas | NCBITaxon:1707 · TaxonMech · TraitMech |
PRIMARY_DEGRADER
CROSS_FEEDER
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ABUNDANT |
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| Rhodopseudomonas capsulata — ontology label: Rhodobacter capsulatus | NCBITaxon:1061 · TaxonMech · TraitMech |
CROSS_FEEDER
PRIMARY_PRODUCER
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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 to Organic Acid Cross-Feeding
CROSS_FEEDINGCellulomonas ATCC 21399 ferments cellulose to organic acids that support anaerobic photoheterotrophic R. capsulata. The abstract does not identify an acid species or demonstrate interpartner sugar transfer.
Source Taxon: Cellulomonas sp. strain ATCC 21399
Target Taxon: Rhodopseudomonas capsulata
Metabolites: cellulose (CHEBI:18246 · MediaIngredientMech · CMMMech), organic acid (CHEBI:64709 · MediaIngredientMech · CMMMech)
Biological Processes:
- cellulose catabolic process (GO:0030245 · PathwayMech)
- fermentation (GO:0006113 · PathwayMech)
Organic-acid provision supplies the phototrophic partner with substrates for nitrogenase-dependent hydrogen production. This substrate connection does not establish reciprocal product-removal dependence.
Evidence
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PMID:16346269 - SUPPORT (IN_VITRO)"produces organic acids during cellulose fermentation"
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PMID:16346269 - SUPPORT (IN_VITRO)"grows photoheterotrophically under anaerobic conditions on organic acids or sugars"
Nitrogenase-Dependent Net Photohydrogen Yield
Illuminated anaerobic cocultures yield hydrogen through the R. capsulata nitrogenase system using cellulose-derived fermentation products. Net hydrogen output does not establish nitrogen fixation, carbon fixation or thermodynamic syntrophy.
Metabolites: dihydrogen (CHEBI:18276 · MediaIngredientMech · CMMMech), cellulose (CHEBI:18246 · MediaIngredientMech · CMMMech)
Evidence
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PMID:16346269 - SUPPORT (IN_VITRO)"photoevolves molecular hydrogen by the nitrogenase system of R. capsulata"
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PMID:16346269 - SUPPORT (IN_VITRO)"cellulose as the sole carbon source"
Uptake Hydrogenase Loss Increases Hydrogen Yield
Cocultures with an uptake-hydrogenase-negative R. capsulata mutant yielded 4.6-6.2 mol H2 per glucose equivalent versus 1.2-4.3 with the wild type. This genotype-dependent net yield is not niche partitioning or a measurement of gross nitrogenase flux.
Metabolites: dihydrogen (CHEBI:18276 · MediaIngredientMech · CMMMech)
Loss of hydrogen uptake reduces a consumption route and increases net hydrogen yield; the mutant comparison does not show that gross nitrogenase production increased.
Evidence
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PMID:16346269 - SUPPORT (IN_VITRO)"hydrogenase-negative mutant produced 4.6 to 6.2 mol of H(2) per mol of glucose equivalent"
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PMID:16346269 - SUPPORT (IN_VITRO)"compared with 1.2 to 4.3 mol for the wild type"
Associated Datasets
| Dataset | Type | Repository | Accession |
|---|---|---|---|
|
Photoproduction of H2 from cellulose by an anaerobic bacterial coculture
PubMed- and PMC-indexed Applied and Environmental Microbiology study of cellulose-dependent hydrogen production by Cellulomonas sp. ATCC 21399 and R. capsulata cocultures. |
PHENOTYPE | OTHER | PMID:16346269 |
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Which transferred acids and production-versus-consumption fluxes account for the net hydrogen difference?
PMID:16346269 abstract supports the organic-acid handoff and genotype comparison. Full methods remain unread. Hydrogen evolution does not by itself establish nitrogen fixation or photosynthetic CO2 assimilation; organism capabilities are not transfer measurements.
Attaches to: ecological_interactions#Cellulose Fermentation to Organic Acid Cross-Feeding, ecological_interactions#Nitrogenase-Dependent Net Photohydrogen Yield, ecological_interactions#Uptake Hydrogenase Loss Increases Hydrogen Yield
Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| Cellulose substrate | cellulose as sole carbon source | N/A |
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| Anaerobic photoheterotrophic condition | anaerobic phototrophic growth on organic acids or sugars | N/A |
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| Uptake hydrogenase genotype | wild-type versus uptake-hydrogenase-negative R. capsulata | N/A |
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Growth Media
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