A defined two-member chlorinated-ethene bioremediation coculture pairing Dehalococcoides mccartyi strain BAV1 with Methanosarcina barkeri strain Fusaro. D. mccartyi BAV1 is corrinoid auxotrophic and requires a cobalamin-type cofactor for organohalide respiration. M. barkeri Fusaro produces extracellular factor III, which did not by itself support Dehalococcoides reductive dechlorination activity, but addition of 5,6-dimethylbenzimidazole enabled guided biosynthesis of cobalamin that supported Dehalococcoides activity and growth. The system is relevant to DOE chlorinated-solvent groundwater bioremediation because it resolves a cofactor-mediated interaction controlling reductive dechlorination.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Dehalococcoides mccartyi BAV1 | NCBITaxon:216389 · TaxonMech · TraitMech |
CROSS_FEEDER
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N/A |
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| Methanosarcina barkeri strain Fusaro — ontology label: Methanosarcina barkeri str. Fusaro | NCBITaxon:269797 · TaxonMech · TraitMech |
CROSS_FEEDER
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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.
DMB-Guided Cobalamin Support
CROSS_FEEDINGDMB amendment enables compatible cobalamin production and supports BAV1 dechlorination and growth in the Fusaro coculture. Native factor III alone does not supply an adequate cofactor under the tested conditions. The experiment supports conditional partner assistance, not endogenous DMB supply or reciprocal nutrient exchange.
Source Taxon: Methanosarcina barkeri strain Fusaro
Target Taxon: Dehalococcoides mccartyi BAV1
Metabolites: cobalamin (CHEBI:30411 · MediaIngredientMech · CMMMech), 5,6-dimethylbenzimidazole (CHEBI:15890 · MediaIngredientMech · CMMMech)
Biological Processes:
- cobalamin biosynthetic process (GO:0009236 · PathwayMech)
- organohalide respiration (GO:0070812 · PathwayMech)
With externally supplied DMB, the partner-associated corrinoid system supplies compatible cofactor and enables BAV1 dechlorination and growth. This does not assign an exclusive donor-versus-recipient remodeling route or imply that DMB is required when compatible cobalamin is supplied directly.
Evidence
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PMID:23479750 - SUPPORT (IN_VITRO)"addition of DMB enabled guided biosynthesis and generated a cobalamin"
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PMID:23479750 - SUPPORT (IN_VITRO)"supported Dehalococcoides' activity and growth"
Factor III Is Insufficient Without DMB
Without DMB or a compatible cobalamin amendment, the tested Fusaro cobamide supply did not adequately support BAV1 reductive dechlorination. This negative compatibility result is not commensalism, active factor-III toxicity or proof that the methanogen inhibits an otherwise adequately supplemented dechlorinator.
Source Taxon: Methanosarcina barkeri strain Fusaro
Target Taxon: Dehalococcoides mccartyi BAV1
Biological Processes:
- organohalide respiration (GO:0070812 · PathwayMech)
Failure to supply an adequate compatible cofactor leaves BAV1 dechlorination constrained in the unamended coculture. This denotes a missing nutritional input, not active inhibition by factor III. DMB-associated cofactor production or direct compatible-cobalamin supplementation can overcome that limitation.
Evidence
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PMID:23479750 - SUPPORT (IN_VITRO)"Neither factor III nor the phenolic cobamides supported Dehalococcoides reductive dechlorination activity"
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PMID:23479750 - SUPPORT (IN_VITRO)"M. barkeri and the Sporomusa sp. cannot fulfil Dehalococcoides' nutritional requirements"
Cobalamin-Dependent Reductive Dechlorination
BAV1 cobalamin-dependent organohalide respiration converts growth-supporting chlorinated ethenes toward ethene; limited cofactor availability can leave incomplete dechlorination and vinyl chloride. This is the recipient phenotype, not BAV1-to-Fusaro cross-feeding. Pooled BAV1, GT and FL2 responses are not all assigned to this pair.
Source Taxon: Dehalococcoides mccartyi BAV1
Metabolites: chloroethene (CHEBI:28509 · MediaIngredientMech · CMMMech), ethene (CHEBI:18153 · MediaIngredientMech · CMMMech), cobalamin (CHEBI:30411 · MediaIngredientMech · CMMMech)
Biological Processes:
- organohalide respiration (GO:0070812 · PathwayMech)
Evidence
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PMID:23479750 - SUPPORT (IN_VITRO)"require vitamin B12 (CN-Cbl) to conserve energy via organohalide respiration"
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PMID:23479750 - SUPPORT (IN_VITRO)"incomplete leading to vinyl chloride (VC) accumulation"
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Which cofactor-production and remodeling routes support BAV1 in the DMB-amended pair?
The cached abstract and indexed primary excerpts support DMB-dependent rescue and native-cobamide insufficiency, not an exclusive cell-resolved route or reciprocal transfer. Complete primary body, figure images and supplements were not retrieved; fine-grained strain/substrate comparisons are therefore not generalized. Preserve the positive rescue and negative compatibility observations without equating absence of support with toxicity. Non-graph follow-up: #1386.
Attaches to: ecological_interactions#DMB-Guided Cobalamin Support, ecological_interactions#Factor III Is Insufficient Without DMB, ecological_interactions#Cobalamin-Dependent Reductive Dechlorination
External Resources
| Name | Repository | Resource ID |
|---|---|---|
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Exact-system cobalamin-guidance publication
Primary publication reporting D. mccartyi BAV1, GT, and FL2 cocultures with M. barkeri Fusaro and acetogens to test guided cobalamin biosynthesis for reductive dechlorination. |
OTHER | PMID:23479750 |
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Open full text for cobalamin-guidance publication
Open-access full text corresponding to the guided cobalamin biosynthesis study. |
OTHER | PMCID:PMC3638461 |
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BAV1 dechlorination phenotype publication
Primary publication describing detoxification of vinyl chloride to ethene by the BAV1 lineage. |
OTHER | PMID:12840758 |
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Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| DMB amendment | 10 microM 5,6-dimethylbenzimidazole | N/A |
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| High cobalamin control | 25 micrograms per liter CN-Cbl | N/A |
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| Limiting cobalamin stress | 1 microgram per liter CN-Cbl | N/A |
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Growth Media
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