A thermophilic syntrophic, obligate two-member anaerobic consortium consisting of Pelotomaculum thermopropionicum, which oxidizes propionate and other organic acids (ethanol, lactate, alcohols) to acetate, CO2, and H2, and Methanothermobacter thermautotrophicus, a hydrogen-utilizing thermophilic methanogen. P. thermopropionicum oxidizes propionate only in coculture with H2-using methanogens, as it uses protons as the electron acceptor with H2 as the electron sink product. The removal of H2 by M. thermautotrophicus is thermodynamically essential for continued propionate oxidation by P. thermopropionicum. This thermophilic syntrophic relationship is fundamental to understanding propionate degradation and methane production at elevated temperatures (55°C) in anaerobic environments such as thermophilic digesters and hot springs.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
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| Pelotomaculum thermopropionicum | NCBITaxon:110500 · TaxonMech · TraitMech |
PRIMARY_DEGRADER
SYNTROPHIC_PARTNER
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N/A |
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| Methanothermobacter thermautotrophicus | NCBITaxon:145262 · TaxonMech · TraitMech |
SYNTROPHIC_PARTNER
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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.
Propionate Oxidation and H2 Production
SYNTROPHYP. thermopropionicum SI grows on propionate in coculture with the hydrogenotrophic methanogen M. thermautotrophicus DeltaH. Preserve the propionate-oxidation/H2-transfer interpretation and the reported 55 degrees C growth optimum, without claiming that the temperature measurement itself proves metabolic flux. Dependence is substrate- and condition-specific: the species paper reports pure-culture growth on pyruvate and fumarate and fumarate reduction, despite absence of dissimilatory sulfate reduction. It does not justify a universal inability to use electron acceptors or grow without a partner.
Source Taxon: Pelotomaculum thermopropionicum
Target Taxon: Methanothermobacter thermautotrophicus
Metabolites: propionate (CHEBI:17272 · MediaIngredientMech · CMMMech), acetate (CHEBI:30089 · MediaIngredientMech · CMMMech), carbon dioxide (CHEBI:16526 · MediaIngredientMech · CMMMech), dihydrogen (CHEBI:18276 · MediaIngredientMech · CMMMech)
Biological Processes:
- propionate catabolic process (GO:0019543 · PathwayMech)
- propionate metabolic process (GO:0019541 · PathwayMech)
H2 supplied during syntrophic propionate oxidation fuels the hydrogenotrophic partner. Preserve this directly implied donor-to-methanogen direction; the species-description abstract does not quantify the exchanged flux or its stoichiometry.
Evidence
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PMID:12361280 - SUPPORT (IN_VITRO)"The strain grew on propionate, ethanol, lactate, 1-butanol, 1-pentanol, 1,3-propanediol, 1-propanol and ethylene glycol in co-culture with the hydrogenotrophic methanogen Methanothermobacter thermautotrophicus strain deltaH(T)"
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PMID:12361280 - SUPPORT (IN_VITRO)"The strain could grow fermentatively on pyruvate and fumarate in pure culture"
Alternative Alcohol and Diol Oxidation
SYNTROPHYThe species paper reports coculture growth on ethanol, lactate, 1-butanol, 1-pentanol, 1,3-propanediol, 1-propanol and ethylene glycol as well as propionate. These positive substrate-use phenotypes support the alternative syntrophic route. The accessible abstract does not identify the carbon products and stoichiometry of every substrate, so acetate and CO2 must not be assigned universally to all alcohols and diols.
Source Taxon: Pelotomaculum thermopropionicum
Target Taxon: Methanothermobacter thermautotrophicus
Metabolites: ethanol (CHEBI:16236 · MediaIngredientMech · CMMMech), lactate (CHEBI:24996 · MediaIngredientMech · CMMMech), butan-1-ol (CHEBI:28885 · MediaIngredientMech · CMMMech), ethylene glycol (CHEBI:30742 · MediaIngredientMech · CMMMech), dihydrogen (CHEBI:18276 · MediaIngredientMech · CMMMech)
Biological Processes:
- fermentation (GO:0006113 · PathwayMech)
PARTIAL - The reported growth of SI with a hydrogenotrophic partner on these alternative substrates supports H2-linked syntrophy. Substrate-resolved H2 yields and carbon-product balances are not exposed in the cited species-description abstract; do not assume every substrate supplies the same acetate/CO2 products.
Evidence
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PMID:12361280 - SUPPORT (IN_VITRO)"The strain grew on propionate, ethanol, lactate, 1-butanol, 1-pentanol, 1,3-propanediol, 1-propanol and ethylene glycol in co-culture with the hydrogenotrophic methanogen Methanothermobacter thermautotrophicus strain deltaH(T)"
Interspecies Hydrogen Transfer and Thermophilic Methanogenesis
SYNTROPHYM. thermautotrophicus is the hydrogenotrophic partner, consuming H2 for methane formation and providing an H2 sink compatible with SI propionate oxidation. The separate 2005 study reports stronger coaggregation on propionate than on ethanol or 1-propanol. Microscopy supports physical association, while Fick-law calculations support substrate-dependent diffusion-distance requirements; those modeled distances are not direct flux measurements. Its Figure4 caption reports 2-BES inhibition of partner hydrogen consumption. Retain these positive observations without attributing all of them to the 2002 species paper or asserting direct electron conduction through filaments.
Source Taxon: Methanothermobacter thermautotrophicus
Target Taxon: Pelotomaculum thermopropionicum
Metabolites: dihydrogen (CHEBI:18276 · MediaIngredientMech · CMMMech), carbon dioxide (CHEBI:16526 · MediaIngredientMech · CMMMech), methane (CHEBI:16183 · MediaIngredientMech · CMMMech)
Biological Processes:
- methanogenesis (GO:0015948 · PathwayMech)
Evidence
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PMID:12361280 - SUPPORT (IN_VITRO)"The strain grew on propionate, ethanol, lactate, 1-butanol, 1-pentanol, 1,3-propanediol, 1-propanol and ethylene glycol in co-culture with the hydrogenotrophic methanogen Methanothermobacter thermautotrophicus strain deltaH(T)"
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PMID:16332758 - SUPPORT (IN_VITRO)"these organisms coaggregated to different degrees depending on the substrate"
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PMID:16332758 - SUPPORT (IN_VITRO)"Hydrogen consumption by ΔH cells was inhibited by adding 2-BES."
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN How should hydrogen-removal feedback and coaggregation be represented after full-method review?
Existing substrate-growth and H2-to-methanogenesis directions remain. PMID16332758 adds positive microscopy and a partner-inhibition lead; its modeled proximity requirement must not be confused with measured flux or electrical conduction. Full main methods and possible separate coaggregation/feedback structure remain research work. A one-community Edison causal dry run exists; no paid report or new node/arrow has been used. Non-graph medium and universal-dependence claims are preserved but not certified.
Attaches to: ecological_interactions#Propionate Oxidation and H2 Production, ecological_interactions#Alternative Alcohol and Diol Oxidation, ecological_interactions#Interspecies Hydrogen Transfer and Thermophilic Methanogenesis
2 evidence item(s)
these organisms coaggregated to different degrees depending on the substrate
The primary abstract reports substrate-dependent physical association; diffusion-distance inference is a separate calculation.
Hydrogen consumption by ΔH cells was inhibited by adding 2-BES.
The primary Figure4 caption reports inhibition of the methanogenic hydrogen sink, not a filament-conduction experiment.
Environmental Factors
| Factor | Value | Unit |
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| Anaerobic Conditions | Strict anaerobic | N/A |
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| Temperature | 55°C | degrees Celsius |
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| pH | 7.0 | N/A |
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| Hydrogen Partial Pressure | Must be maintained at low levels | N/A |
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| Coaggregation | Present | N/A |
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Growth Media
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