Two simplified methanogenic consortia (DIETsimp) constructed by top-down selection from cow manure combined with paddy soil or marine sediment inocula for high-efficiency conversion of lignocellulose to methane via direct interspecies electron transfer (DIET). Metagenomic analysis identified Methanosarcina mazei, capable of accepting electrons via DIET, as the dominant archaeon, and the electroactive bacteria Sphaerochaeta globosa and Clostridium aceticum as the dominant bacteria. The proposed DIET-based methanogenic pathway has S. globosa and C. aceticum metabolizing intermediates (xylose, glucose, pyruvate, acetate) and transferring electrons to M. mazei for reduction of CO2 to methane. Both consortia shortened methanogenesis periods and increased methane production rates relative to conventional anaerobic digestion.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Methanosarcina mazei | NCBITaxon:2209 |
SYNTROPHIC_PARTNER
ELECTRON_ACCEPTOR
ELECTROTROPH
|
N/A |
|
|||
| Sphaerochaeta globosa | NCBITaxon:1131703 |
PRIMARY_DEGRADER
ELECTRON_DONOR
ELECTROGEN
SYNTROPHIC_PARTNER
|
N/A |
|
|||
| Clostridium aceticum | NCBITaxon:84022 |
PRIMARY_DEGRADER
ELECTRON_DONOR
ELECTROGEN
SYNTROPHIC_PARTNER
|
N/A |
|
|||
Ecological Interactions
DIET syntrophy from S. globosa to M. mazei
SYNTROPHYSource Taxon: Sphaerochaeta globosa
Target Taxon: Methanosarcina mazei
Metabolites: xylose (CHEBI:18222), D-glucose (CHEBI:17634), pyruvate (CHEBI:15361), acetate (CHEBI:30089), carbon dioxide (CHEBI:16526), methane (CHEBI:16183)
Evidence
-
PMID:42229598 - SUPPORT (IN_VITRO)"S. globosa and C. aceticum metabolized intermediates (e.g. xylose, glucose, pyruvate and acetate) and transferred electrons to M. mazei for the reduction of CO2 to methane"
DIET syntrophy from C. aceticum to M. mazei
SYNTROPHYSource Taxon: Clostridium aceticum
Target Taxon: Methanosarcina mazei
Metabolites: xylose (CHEBI:18222), D-glucose (CHEBI:17634), pyruvate (CHEBI:15361), acetate (CHEBI:30089), carbon dioxide (CHEBI:16526), methane (CHEBI:16183)
Evidence
-
PMID:42229598 - SUPPORT (IN_VITRO)"S. globosa and C. aceticum metabolized intermediates (e.g. xylose, glucose, pyruvate and acetate) and transferred electrons to M. mazei for the reduction of CO2 to methane"
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Are the S. globosa→M. mazei and C. aceticum→M. mazei DIET pathways experimentally validated (direct interspecies electron transfer vs H2/formate mediation), and is there any causal dependency between the two parallel donor→methanogen relationships?
An Edison causal-graph pass (PMID:42229598) found no justifiable directed causal edge for this consortium: both interactions are recorded as "Proposed DIET pathway", the primary full text was inaccessible, and no perturbation (donor-removal, inhibitor, mono-/co-culture, or knockout) evidence was retrieved. The source supports two parallel donor→methanogen proposals, not a causal dependency of one on the other, so no `downstream` edge was added. Neutral-red-mediated electron delivery to M. mazei reported in a different system must not be imported here without exact-system verification.
Attaches to: ecological_interactions#DIET syntrophy from S. globosa to M. mazei, ecological_interactions#DIET syntrophy from C. aceticum to M. mazei
1 evidence item(s)
during anaerobic digestion of lignocellulose that S. globosa and C. aceticum metabolized intermediates
The consortium role is stated at the level of intermediate metabolism / proposed DIET, without a validated or perturbation-tested causal mechanism — the basis for the knowledge gap.