Syntrophobacter-Methanobacterium Syntrophic Consortium

Community ID CommunityMech:000068

Ecological State STABLE

Environment anaerobic environment — ontology label: active anaerobic enrichment culturing unit
ENVO:01001825 · HabitatMech ↗

A syntrophic, obligate two-member anaerobic consortium consisting of Syntrophobacter fumaroxidans, which oxidizes propionate to acetate, and Methanobacterium formicicum, a hydrogen and formate-utilizing methanogen. S. fumaroxidans degrades propionate via the methylmalonyl-CoA pathway only in coculture with H2/formate-using archaea, as it uses protons as the electron acceptor with H2 and formate as electron sink products. The removal of H2 and formate by M. formicicum is thermodynamically essential for continued propionate oxidation by S. fumaroxidans. This syntrophic relationship is fundamental to understanding methane production from propionate in anaerobic environments such as digesters, sediments, and wastewater treatment systems, playing a critical role in biogeochemical cycling.

Taxonomy

Taxon	Ontology ID	Functional Roles	Abundance
Syntrophobacter fumaroxidans	NCBITaxon:119484 · TaxonMech · TraitMech	PRIMARY_DEGRADER SYNTROPHIC_PARTNER	N/A
doi:10.1099/00207713-48-4-1383 - SUPPORT (IN_VITRO) "The name Syntrophobacter fumaroxidans is proposed; strain MPOBT (= DSM 10017T) is the type strain."
Methanobacterium formicicum	NCBITaxon:2162 · TaxonMech · TraitMech	SYNTROPHIC_PARTNER	N/A
PMID:29611893 - SUPPORT (IN_VITRO) "We performed a proteome analysis of S. fumaroxidans growing with propionate axenically with sulfate or fumarate, and in syntrophy with Methanospirillum hungatei, Methanobacterium formicicum or Desulfovibrio desulfuricans" doi:10.1099/00207713-48-4-1383 - PARTIAL (IN_VITRO) "It oxidized propionate syntrophically in co-culture with the hydrogen- and formate-utilizing Methanospirillum hungateii, and was able to oxidize propionate and other organic compounds in pure culture with sulfate or fumarate as the electron acceptor"

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.

Taxon

Syntrophy

Other

Propionate Oxidation and H2/Formate Production

SYNTROPHY

S. fumaroxidans oxidizes propionate in syntrophy with M. formicicum, releasing reducing equivalents through hydrogen and/or formate. The methylmalonyl-CoA pathway produces acetate and inorganic carbon. Partner consumption maintains low hydrogen partial pressure and formate concentration; these are different physical quantities. This is the tested methanogenic growth context, not universal partner dependence: sulfate or fumarate can support axenic growth. PARTIAL: comparative protein abundance and homology support proposed Fdh1/Hox confurcation and Fdh2/Hyn reverse-electron-transport roles, not direct demonstration of every enzyme assignment or the fraction of electrons carried by each route in this pair.

Source Taxon: Syntrophobacter fumaroxidans

Target Taxon: Methanobacterium formicicum

Metabolites: propionate (CHEBI:17272 · MediaIngredientMech · CMMMech), acetate (CHEBI:30089 · MediaIngredientMech · CMMMech), dihydrogen (CHEBI:18276 · MediaIngredientMech · CMMMech), formate (CHEBI:15740 · MediaIngredientMech · CMMMech)

Biological Processes:

propionate metabolic process (GO:0019541 · PathwayMech)
propionate catabolic process (GO:0019543 · PathwayMech)

Downstream Effects:

→ Interspecies Electron Transfer and Methanogenesis

DIRECTLY IMPLIED: reducing equivalents released during bacterial propionate oxidation supply M. formicicum through hydrogen and/or formate for methanogenesis. The evidence does not quantify their separate fluxes in this pair.

Evidence

PMID:29611893 - SUPPORT (IN_VITRO)

"We performed a proteome analysis of S. fumaroxidans growing with propionate axenically with sulfate or fumarate, and in syntrophy with Methanospirillum hungatei, Methanobacterium formicicum or Desulfovibrio desulfuricans"
PMID:29611893 - PARTIAL (IN_VITRO)

"a very plausible candidate for a confurcating-type of formate dehydrogenase"
PMID:29611893 - PARTIAL (IN_VITRO)

"Hox is most probably a confurcating hydrogenase involved in energy conservation"
doi:10.3390/w16243551 - SUPPORT (IN_VITRO)

"of all four formate dehydrogenases (FDH1, FDH2, FDH3, FDH4) was down-regulated under formate stress"
doi:10.3390/w16243551 - PARTIAL (IN_VITRO)

"the downregulation of RNA transcription of formate dehydrogenase (FDH) and hydrogenase (Hyd) related to MMC pathway may be the main reason for the inhibition of syntrophic propionate oxidation"

Interspecies Electron Transfer and Methanogenesis

SYNTROPHY

M. formicicum acts as the hydrogen/formate-using methanogenic partner of S. fumaroxidans. Carrier consumption supports methane formation and relieves the thermodynamic constraint on propionate oxidation. Low hydrogen partial pressure and low formate concentration are distinct constraints; formate is not a gas pressure. The comparative proteome suggests an important formate route but does not independently quantify exact-pair carrier partitioning.

Source Taxon: Methanobacterium formicicum

Target Taxon: Syntrophobacter fumaroxidans

Metabolites: dihydrogen (CHEBI:18276 · MediaIngredientMech · CMMMech), formate (CHEBI:15740 · MediaIngredientMech · CMMMech), methane (CHEBI:16183 · MediaIngredientMech · CMMMech)

Biological Processes:

methanogenesis (GO:0015948 · PathwayMech)

Downstream Effects:

→ Propionate Oxidation and H2/Formate Production

DIRECTLY IMPLIED feedback: hydrogen/formate consumption by M. formicicum lowers hydrogen partial pressure and formate concentration, enabling continued propionate oxidation. This retains the thermodynamic cooperation inferred from syntrophic versus electron-acceptor-supported axenic growth; it is not a selective carrier-removal assay in this exact pair.

→ Syntrophic Propionate-to-Methane Conversion

Methanogenic consumption of bacterially supplied reducing equivalents couples propionate oxidation to methane production. Cooperation is reciprocal, but the carrier transfer described here is bacterial-to-methanogen, not bidirectional donation.

Evidence

PMID:29611893 - SUPPORT (IN_VITRO)

"We performed a proteome analysis of S. fumaroxidans growing with propionate axenically with sulfate or fumarate, and in syntrophy with Methanospirillum hungatei, Methanobacterium formicicum or Desulfovibrio desulfuricans"
PMID:29611893 - SUPPORT (IN_VITRO)

"During syntrophic growth, S. fumaroxidans needs to transfer electrons via hydrogen and/or formate to a syntrophic partner."
PMID:29611893 - PARTIAL (IN_VITRO)

"It has long been speculated that formate plays a more important role than hydrogen as an electron carrier"

Syntrophic Propionate-to-Methane Conversion

The S. fumaroxidans-M. formicicum coculture joins propionate oxidation to methanogenesis. This community conversion is the outcome of the two existing partner processes, not a third pairwise exchange. Acetate remains a bacterial product, so this does not assert complete mineralization of propionate carbon to methane.

Participating Taxa: Syntrophobacter fumaroxidans, Methanobacterium formicicum

Metabolites: propionate (CHEBI:17272 · MediaIngredientMech · CMMMech), formate (CHEBI:15740 · MediaIngredientMech · CMMMech), methane (CHEBI:16183 · MediaIngredientMech · CMMMech)

Biological Processes:

propionate catabolic process (GO:0019543 · PathwayMech)
methanogenesis (GO:0015948 · PathwayMech)

Evidence

PMID:29611893 - SUPPORT (IN_VITRO)

"We performed a proteome analysis of S. fumaroxidans growing with propionate axenically with sulfate or fumarate, and in syntrophy with Methanospirillum hungatei, Methanobacterium formicicum or Desulfovibrio desulfuricans"

Knowledge gaps & discussions (1)

KNOWLEDGE_GAP OPEN Which curated claims about this consortium rest on exact-pair (S. fumaroxidans + M. formicicum) evidence, and which were imported from S. fumaroxidans + M. hungatei experiments?

Several evidence items on this record quote doi:10.1099/00207713-48-4-1383 (Harmsen et al. 1998), whose syntrophic coculture passage names *Methanospirillum hungateii*, not this record's partner *Methanobacterium formicicum*. Two of those items previously carried explanations asserting that the passage established M. formicicum as the partner; they have been corrected and downgraded to PARTIAL, and exact-pair support has been added from PMID:29611893 (Sedano-Nunez et al. 2018), which explicitly grew S. fumaroxidans in syntrophy with M. formicicum. The residual gap: the frequently cited biochemical formate-transfer and FDH/hydrogenase transcription results for this system were obtained with M. hungatei, so carrier apportionment ("formate is the dominant carrier") must NOT be curated as an exact-pair finding. PARTLY RESOLVED: the 2024 exact-pair perturbation study (Li et al., Water 16:3551, doi:10.3390/w16243551) is now ingested - its full text was supplied by a curator from the publisher PDF, since the journal is absent from PubMed and Europe PMC and MDPI blocks programmatic download. Its graded-formate results for the exact S. fumaroxidans-M. formicicum coculture are curated under the Exogenous Formate Dosage environmental factor, and its FDH downregulation result on the Propionate Oxidation interaction. Two cautions came out of that ingestion: (a) the paper runs an anaerobic-sludge system ALONGSIDE the coculture, and sludge-only results (e.g. Acetobacterium homoacetogenesis rising with formate dose) must not be attributed to this two-member consortium; (b) the dose response is non-monotonic - 30 mM recovers in the later stage - so it is NOT a simple ">=30 mM inhibits" threshold. Still open: carrier apportionment between H2 and formate for the M. formicicum pair specifically, which no retrieved study resolves with an isotope or selective-inhibition experiment. Batch112: the graph now uses exact-pair proteomic cultivation evidence rather than the 1998 M. hungatei passage as full support. Main-text Fdh1/Hox assignments are qualified mechanistic interpretations; no exact-pair hydrogen/formate flux ratio is inferred. The 2024 transcription passages were rechecked in the existing curator-supplied text; fresh publisher retrieval was unavailable. Hydrogen partial pressure is distinguished from formate concentration.

Attaches to: ecological_interactions#Propionate Oxidation and H2/Formate Production, ecological_interactions#Interspecies Electron Transfer and Methanogenesis

2 evidence item(s)

IN_VITRO SUPPORT PMID:29611893

We performed a proteome analysis of S. fumaroxidans growing with propionate axenically with sulfate or fumarate, and in syntrophy with Methanospirillum hungatei, Methanobacterium formicicum or Desulfovibrio desulfuricans

The one curated reference that studies the exact pair alongside the M. hungatei pairing - the basis for separating exact-pair from imported claims.

IN_VITRO PARTIAL doi:10.1099/00207713-48-4-1383

It oxidized propionate syntrophically in co-culture with the hydrogen- and formate-utilizing Methanospirillum hungateii

The misattribution source - this passage names M. hungateii and cannot establish M. formicicum as the partner.

Environmental Factors

Factor	Value	Unit
Exogenous Formate Dosage	5-10 mM promotes; 50 mM inhibits	mM
doi:10.3390/w16243551 - SUPPORT (IN_VITRO) "Syntrophobacter fumaroxidans and Methanobacterium formicicum to establish a co-culture system to reveal the molecular response mechanism of MMC pathway under formate stress" doi:10.3390/w16243551 - SUPPORT (IN_VITRO) "The degradation efficiency of propionate in the experimental groups with dosages of 5 and 10 mM was obviously higher than that of the other groups" doi:10.3390/w16243551 - SUPPORT (IN_VITRO) "The system in the 50 mM group showed significant accumulation of propionate at 5~7 days" doi:10.3390/w16243551 - PARTIAL (IN_VITRO) "the metabolic efficiency of propionate in the medium concentration group (30 mM) was improved instead of inhibited in the later stage"
Anaerobic Conditions	Strict anaerobic	N/A
doi:10.1099/00207713-48-4-1383 - SUPPORT (IN_VITRO) "A syntrophic propionate-oxidizing bacterium, strain MPOBT, was isolated from a culture enriched from anaerobic granular sludge"
Hydrogen and Formate Partial Pressure	Must be maintained at low levels	N/A
PMID:29611893 - SUPPORT (IN_VITRO) "fumaroxidans mainly used formate for electron release and that different confurcating mechanisms were used in its sulfidogenic metabolism"
Ecological Relevance	Biogeochemical cycling	N/A
doi:10.1099/00207713-48-4-1383 - SUPPORT (IN_VITRO) "A syntrophic propionate-oxidizing bacterium, strain MPOBT, was isolated from a culture enriched from anaerobic granular sludge"

Growth Media

anoxic bicarbonate-buffered basal medium (Stams et al., 1993)

Temperature 37 °C

Atmosphere ANAEROBIC

Preparation notes: S. fumaroxidans (DSM 10017)-M. formicicum (DSM 1535) coculture grown on 30 mM propionate without added electron acceptor under anoxic conditions; batch cultured in triplicate.

Evidence

PMID:29611893

"Syntrophobacter fumaroxidans MPOBT (DSM 10017) was cultivated under anoxic conditions in basal medium as described previously"

PMID:29611893

"All organisms were batch cultured in triplicate at 37°C in 1 l flasks"

PMID:29611893

"Cocultures of S. fumaroxidans with Methanospirillum hungatei strain JF1T (DSM 864) or Methanobacterium formicicum MFT (DSM 1535) were grown with 30 mM of propionate without electron acceptor"

Cross-Mech Suite Links

Explore related entities across the CultureBotAI X-Mech knowledge bases:

HabitatMech: anaerobic environment ↗ TaxonMech: Syntrophobacter fumaroxidans ↗ TraitMech: Syntrophobacter fumaroxidans ↗ TaxonMech: Methanobacterium formicicum ↗ TraitMech: Methanobacterium formicicum ↗ CMMMech (Critical Minerals & REE) ↗ CultureMech Growth Media ↗ PathwayMech Pathways ↗