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Geobacter-Methanosarcina DIET Community

Ecological State STABLE
Environment sediment
ENVO:00002007
Source File Geobacter_Methanosarcina_DIET.yaml

A syntrophic two-member consortium consisting of Geobacter metallireducens and Methanosarcina barkeri that performs direct interspecies electron transfer (DIET) during ethanol oxidation. G. metallireducens oxidizes ethanol and transfers electrons directly to M. barkeri via electrically conductive pili (e-pili), bypassing the need for diffusible electron carriers like H2 or formate. M. barkeri uses these electrons to reduce CO2 to methane. This coculture forms aggregates and achieves stoichiometric conversion of ethanol to methane via DIET. Unlike hydrogen-mediated syntrophy, DIET relies on biological electrical connections between cells, with pili serving as conduits for long-range electron transfer. M. barkeri is unique as a methanogen capable of using either H2 or electrons from DIET for CO2 reduction, making it a model organism for studying electrical connections in microbial communities.

Taxonomy

Taxon Ontology ID Functional Roles Abundance
Geobacter metallireducens NCBITaxon:28232
PRIMARY_DEGRADER SYNTROPHIC_PARTNER
N/A
Methanosarcina barkeri NCBITaxon:2208
SYNTROPHIC_PARTNER
N/A

Ecological Interactions

Ethanol Oxidation and Direct Electron Transfer

SYNTROPHY

Source Taxon: Geobacter metallireducens

Metabolites: ethanol (CHEBI:16236), acetate (CHEBI:30089)

Biological Processes:

Downstream Effects:
→ Direct Electron Acceptance and Methanogenesis

Evidence

  • PMID:24837373 - SUPPORT (IN_VITRO)
    "Amendments of granular activated carbon permitted the pilin-deficient G"
  • PMID:24837373 - SUPPORT (IN_VITRO)
    "Cocultures could not be initiated with a pilin-deficient G. metallireducens strain, suggesting that long-range electron transfer along pili was important for DIET"
  • PMID:24837373 - SUPPORT (IN_VITRO)
    "Amendments of granular activated carbon permitted the pilin-deficient G. metallireducens isolates to share electrons with M. barkeri"

Direct Electron Acceptance and Methanogenesis

MUTUALISM

Source Taxon: Methanosarcina barkeri

Metabolites: methane (CHEBI:16183), carbon dioxide (CHEBI:16526)

Biological Processes:

Evidence

  • PMID:24837373 - SUPPORT (IN_VITRO)
    "barkeri is genetically tractable,making it a model organism for elucidating mechanisms by which methanogens make biological electrical connections with other cells."
  • PMID:24837373 - SUPPORT (IN_VITRO)
    "Direct interspecies electron transfer (DIET) is potentially an effective form of syntrophy in methanogenic communities, but little is known about the"

Environmental Factors

Factor Value Unit
Anaerobic Conditions Strict anaerobic N/A
Cell Aggregation Required for DIET N/A
Pili Expression Essential for DIET initiation N/A
Conductive Material Substitution Granular activated carbon can replace pili N/A