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Cellulose-to-Methane Quad-Culture SynCom

Community ID CommunityMech:000089
Ecological State ENGINEERED
Environment laboratory bioreactor — ontology label: laboratory environment
ENVO:01001405 · HabitatMech ↗

A four-species anaerobic synthetic community coupling cellulose degradation, sulfate reduction, and methanogenesis.

Taxonomy

Taxon Ontology ID Functional Roles Abundance
Ruminiclostridium cellulolyticum NCBITaxon:1521 · TaxonMech · TraitMech
PRIMARY_DEGRADER
N/A
  • PMID:36847519 - SUPPORT (IN_VITRO)
    "Here, we constructed a quad-culture consisting of a cellulolytic bacterium (Ruminiclostridium cellulolyticum), a hydrogenotrophic methanogen (Methanospirillum hungatei), an acetoclastic methanogen (Methanosaeta concilii), and a sulfate-reducing bacterium (Desulfovibrio vulgaris)."
Methanospirillum hungatei — ontology label: Methanospirillum hungatei JF-1 NCBITaxon:323259 · TaxonMech · TraitMech
SYNTROPHIC_PARTNER
N/A
  • PMID:36847519 - SUPPORT (IN_VITRO)
    "Here, we constructed a quad-culture consisting of a cellulolytic bacterium (Ruminiclostridium cellulolyticum), a hydrogenotrophic methanogen (Methanospirillum hungatei), an acetoclastic methanogen (Methanosaeta concilii), and a sulfate-reducing bacterium (Desulfovibrio vulgaris)."
Methanosaeta concilii — ontology label: Methanothrix soehngenii NCBITaxon:2223 · TaxonMech · TraitMech
SYNTROPHIC_PARTNER
N/A
  • PMID:36847519 - SUPPORT (IN_VITRO)
    "Here, we constructed a quad-culture consisting of a cellulolytic bacterium (Ruminiclostridium cellulolyticum), a hydrogenotrophic methanogen (Methanospirillum hungatei), an acetoclastic methanogen (Methanosaeta concilii), and a sulfate-reducing bacterium (Desulfovibrio vulgaris)."
Desulfovibrio vulgaris — ontology label: Nitratidesulfovibrio vulgaris NCBITaxon:881 · TaxonMech · TraitMech
SYNTROPHIC_PARTNER
N/A
  • PMID:36847519 - SUPPORT (IN_VITRO)
    "Here, we constructed a quad-culture consisting of a cellulolytic bacterium (Ruminiclostridium cellulolyticum), a hydrogenotrophic methanogen (Methanospirillum hungatei), an acetoclastic methanogen (Methanosaeta concilii), and a sulfate-reducing bacterium (Desulfovibrio vulgaris)."

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.

Ecological interaction network for Cellulose-to-Methane Quad-Culture SynCom Bipartite graph where circles represent taxa and non-circular symbols represent interactions, with distinct shapes and colours for cross-feeding, syntrophy, competition.
Taxon
Cross-feeding
Syntrophy
Competition

Cellulose Cross-Feeding to Methane

CROSS_FEEDING

The four-member culture converts cellulose to methane through cross-feeding. Methane output and cellulose degradation showed different higher-order responses. Organism-resolved exchange routes require the assay and modeling qualifications below; higher total output does not establish reciprocal fitness.

Metabolites: cellulose (CHEBI:18246 · MediaIngredientMech · CMMMech), methane (CHEBI:16183 · MediaIngredientMech · CMMMech)

Biological Processes:

Evidence

  • PMID:36847519 - SUPPORT (IN_VITRO)
    "cooperated via cross-feeding to produce methane using cellulose"

R. cellulolyticum acetate cross-feeding to M. concilii

CROSS_FEEDING

R. cellulolyticum-derived acetate supports the acetoclastic M. concilii route. Culture outcomes support this direction, while the sulfate-associated increase in handoff is inferred from fitted stoichiometric fluxes, not directly traced carbon transfer.

Source Taxon: Ruminiclostridium cellulolyticum

Target Taxon: Methanosaeta concilii

Metabolites: acetate (CHEBI:30089 · MediaIngredientMech · CMMMech)

Biological Processes:

Downstream Effects:
→ Cellulose Cross-Feeding to Methane

Acetate cross-fed to M. concilii drives acetoclastic methanogenesis, one of the two routes to community methane output.

Evidence

  • PMID:36847519 - SUPPORT (IN_VITRO)
    "cross-feeding of acetate from a cellulolytic bacterium to an acetoclastic methanogen"
  • PMID:36847519 - PARTIAL (COMPUTATIONAL)
    "sulfate addition increased both the production of acetate and lactate by R. cellulolyticum and their consumption by M. concilii and D. vulgaris"

R. cellulolyticum lactate cross-feeding to D. vulgaris

CROSS_FEEDING

PARTIAL - the source proposes lactate transfer from R. cellulolyticum to D. vulgaris, but could not resolve lactate versus alternative intermediates. Lactate oxidation to H2 was unfavorable at the studied H2 pressures; pyruvate or alanine remain possible donors.

Source Taxon: Ruminiclostridium cellulolyticum

Target Taxon: Desulfovibrio vulgaris

Metabolites: lactate (CHEBI:24996 · MediaIngredientMech · CMMMech)

Downstream Effects:
→ Proposed D. vulgaris H2 syntrophy to M. hungatei

HYPOTHESIZED - transferred lactate or another oxidizable intermediate could support D. vulgaris H2 provision. The specific lactate-to-H2 handoff is not identified uniquely by the data.

Evidence

  • PMID:36847519 - PARTIAL (IN_VITRO)
    "These results suggest that D. vulgaris fermented lactate produced by R. cellulolyticum to H2"

Proposed D. vulgaris H2 syntrophy to M. hungatei

SYNTROPHY

PARTIAL - D. vulgaris is proposed to supply hydrogen to M. hungatei under limited sulfate. The donor substrate and flux are poorly constrained; the type records proposed syntrophy, not demonstrated obligate dependence. With sulfate addition, D. vulgaris can instead compete for hydrogen.

Source Taxon: Desulfovibrio vulgaris

Target Taxon: Methanospirillum hungatei

Metabolites: dihydrogen (CHEBI:18276 · MediaIngredientMech · CMMMech)

Biological Processes:

Downstream Effects:
→ Cellulose Cross-Feeding to Methane

HYPOTHESIZED - D. vulgaris-derived H2 could contribute to the hydrogenotrophic part of methane output. The D. vulgaris-specific contribution remains unresolved among alternative fitted routes.

Evidence

  • PMID:36847519 - PARTIAL (IN_VITRO)
    "D. vulgaris enhanced hydrogenotrophic methanogenesis, likely by producing additional hydrogen from lactate fermentation"

M. hungatei H2 removal relieves R. cellulolyticum product inhibition

SYNTROPHY

PARTIAL - H2 production inferred from the Rc/Mh biculture stoichiometry exceeded the Rc monoculture value, supporting the proposed relief of product inhibition by H2 consumption. This is not a direct pressure intervention or evidence of acetate-specific mediation.

Source Taxon: Methanospirillum hungatei

Target Taxon: Ruminiclostridium cellulolyticum

Metabolites: dihydrogen (CHEBI:18276 · MediaIngredientMech · CMMMech)

Evidence

  • PMID:36847519 - PARTIAL (COMPUTATIONAL)
    "This indicates that M. hungatei promoted H2 production by R. cellulolyticum through the alleviation of product inhibition"

D. vulgaris–M. hungatei competition for H2

COMPETITION

PARTIAL - sulfate-associated H2 competition is inferred to redirect reducing equivalents toward D. vulgaris. Zero hydrogenotrophic flux is a fitted model result, not measured complete cessation: the M. hungatei proteome fraction remained 3%, and other electron donors or transfer routes were discussed.

Source Taxon: Desulfovibrio vulgaris

Target Taxon: Methanospirillum hungatei

Metabolites: dihydrogen (CHEBI:18276 · MediaIngredientMech · CMMMech), sulfate (CHEBI:16189 · MediaIngredientMech · CMMMech)

Biological Processes:

Downstream Effects:
→ Proposed D. vulgaris H2 syntrophy to M. hungatei

HYPOTHESIZED - sulfate-supported D. vulgaris H2 consumption could limit the proposed transfer to M. hungatei. Zero hydrogenotrophic flux is model-inferred, not proven cessation of methanogen activity.

→ Cellulose Cross-Feeding to Methane

PARTIAL - the model attributes lower methane output to reduced H2 availability for hydrogenotrophic methanogenesis; the attribution is not an independently isolated mediator.

Evidence

  • PMID:36847519 - PARTIAL (IN_VITRO)
    "competition of H2 between a sulfate reducing bacterium and a hydrogenotrophic methanogen"
  • PMID:36847519 - PARTIAL (COMPUTATIONAL)
    "the addition of sulfate halted hydrogenotrophic methanogenesis in M. hungatei"
  • PMID:36847519 - PARTIAL (COMPUTATIONAL)
    "The main reason for decreased CH4 production was the sharp decrease in H2 available for the hydrogenotrophic methanogen"

Knowledge gaps & discussions (2)

KNOWLEDGE_GAP OPEN Does D. vulgaris fermentation of lactate to acetate and CO2 causally enhance acetoclastic methanogenesis by M. concilii, i.e. is there a second (D. vulgaris-derived) carbon route to methane beyond the direct R. cellulolyticum → M. concilii hand-off?

If confirmed, D. vulgaris would be a secondary acetate/CO2 supplier to the acetoclastic methanogen, adding a parallel carbon route to methane and changing how the causal graph attributes methane output between the two carbon sources. The source paper proposes it mechanistically ("it may be") but does not demonstrate the D. vulgaris → M. concilii carbon edge directly, so it is recorded here as a knowledge gap rather than asserted as an ecological interaction.

Attaches to: ecological_interactions#R. cellulolyticum acetate cross-feeding to M. concilii

1 evidence item(s)
IN_VITRO PARTIAL PMID:36847519

Mechanistically, it may be that D. vulgaris enhances methanogenesis by producing the substrates CO2, acetate, and H2 and removing lactate

The authors state the D. vulgaris → methanogen carbon contribution as a hypothesis ("it may be"), not a demonstrated causal edge — the basis for filing it as a knowledge gap.

KNOWLEDGE_GAP OPEN Which donor substrates and pressure-dependent exchanges uniquely explain the sulfate response?

PMID:36847519 admits alternative optimal flux solutions and poorly constrained Dv exchanges. Protein abundance does not validate every flux direction, and persistent Mh protein prevents equating fitted zero flux with eradication. Preserve the existing open Dv-to-Mc hypothesis; no route from the separate 2025 panel is imported. Control means no added sulfate, not chemically sulfate-free.

Attaches to: ecological_interactions#Cellulose Cross-Feeding to Methane, ecological_interactions#R. cellulolyticum acetate cross-feeding to M. concilii, ecological_interactions#R. cellulolyticum lactate cross-feeding to D. vulgaris, ecological_interactions#Proposed D. vulgaris H2 syntrophy to M. hungatei, ecological_interactions#M. hungatei H2 removal relieves R. cellulolyticum product inhibition, ecological_interactions#D. vulgaris–M. hungatei competition for H2

Environmental Factors

Factor Value Unit
defined synthetic community design Rational functional-guild assembly of cellulolytic, sulfate-reducing, hydrogenotrophic methanogenic, and acetoclastic methanogenic members. N/A
  • PMID:36847519 - SUPPORT (IN_VITRO)
    "Here, we constructed a quad-culture consisting of a cellulolytic bacterium (Ruminiclostridium cellulolyticum), a hydrogenotrophic methanogen (Methanospirillum hungatei), an acetoclastic methanogen (Methanosaeta concilii), and a sulfate-reducing bacterium (Desulfovibrio vulgaris)."

Growth Media

modified VM medium (10 g/L cellulose as sole carbon source)

Temperature 34 °C
Atmosphere ANAEROBIC

Preparation notes: All cultures grown anaerobically in triplicate on cellulose as the sole carbon source; about 5 × 10^7 cells inoculated per species; sulfate-perturbation treatment received additional sulfate versus the control condition.

Evidence

PMID:36847519

"All fermentation experiments were carried out in 160 mL serum bottles with 20 mL of modified VM medium containing 10 g/L cellulose; the chamber gas contained 3% H2 and 97% N2."

PMID:36847519

"All cultures were incubated at 34°C with shaking at 200 rpm for 7 days and sampled each day."

PMID:36847519

"All cultures were grown anaerobically in triplicate using the same medium with cellulose as the sole carbon source."

Cross-Mech Suite Links

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

HabitatMech: laboratory bioreactor ↗ TaxonMech: Ruminiclostridium cellulolyticum ↗ TraitMech: Ruminiclostridium cellulolyticum ↗ TaxonMech: Methanospirillum hungatei ↗ TraitMech: Methanospirillum hungatei ↗ TaxonMech: Methanosaeta concilii ↗ TraitMech: Methanosaeta concilii ↗ TaxonMech: Desulfovibrio vulgaris ↗ TraitMech: Desulfovibrio vulgaris ↗ CultureMech Growth Media ↗ PathwayMech Pathways ↗