A defined two-member anaerobic syntrophic coculture in which Dehalococcoides mccartyi strain 195 reductively dechlorinates trichloroethene while Syntrophomonas wolfei ferments butyrate or crotonate-derived carbon to provide hydrogen and acetate. The system is relevant to chlorinated-solvent groundwater bioremediation because it models interspecies hydrogen transfer and metabolite exchange that support TCE dechlorination by Dehalococcoides-containing communities.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Dehalococcoides mccartyi 195 | NCBITaxon:243164 · TaxonMech · TraitMech |
PRIMARY_DEGRADER
SYNTROPHIC_PARTNER
|
N/A |
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| Syntrophomonas wolfei | NCBITaxon:863 · TaxonMech · TraitMech |
SECONDARY_FERMENTER
SYNTROPHIC_PARTNER
|
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.
Butyrate Fermentation Supporting TCE Dechlorination
SYNTROPHYS. wolfei ferments butyrate to provide hydrogen and acetate while strain 195 consumes hydrogen for TCE reductive dechlorination, supporting favorable fermentative energetics. This positive coupling concerns the butyrate-fed, externally cobalamin-supplemented coculture; crotonate comparisons and donor-limited threshold assays are distinct conditions.
Source Taxon: Syntrophomonas wolfei
Target Taxon: Dehalococcoides mccartyi 195
Metabolites: butyrate (CHEBI:17968 · MediaIngredientMech · CMMMech), dihydrogen (CHEBI:18276 · MediaIngredientMech · CMMMech), acetate (CHEBI:30089 · MediaIngredientMech · CMMMech), trichloroethene (CHEBI:16602 · MediaIngredientMech · CMMMech)
Biological Processes:
- butyrate catabolic process (GO:0046359 · PathwayMech)
- interspecies interaction between organisms (GO:0044419 · PathwayMech)
Hydrogen from S. wolfei butyrate oxidation supplies the electron donor for strain-195 TCE dechlorination, while recipient consumption maintains a favorable hydrogen sink. The separate donor-limited minimum-threshold assay is not the routine culture concentration. Later residual butyrate consumption and cometabolic vinyl-chloride conversion do not establish continued growth after the growth-supporting acceptors are depleted.
Evidence
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PMID:25576615 - SUPPORT (IN_VITRO)"using butyrate as an electron donor and carbon source"
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PMID:25576615 - SUPPORT (IN_VITRO)"Aqueous H2 concentrations ranged from 24 to 180 nM"
Reductive Dechlorination by Dehalococcoides
Strain 195 uses hydrogen for reductive dechlorination of TCE and cis-DCE toward vinyl chloride in the coculture. Subsequent vinyl-chloride-to-ethene conversion is cometabolic, not demonstrated growth-coupled vinyl-chloride respiration. This recipient phenotype is not nutrient transfer from strain 195 to S. wolfei.
Source Taxon: Dehalococcoides mccartyi 195
Metabolites: trichloroethene (CHEBI:16602 · MediaIngredientMech · CMMMech), chloroethene (CHEBI:28509 · MediaIngredientMech · CMMMech), ethene (CHEBI:18153 · MediaIngredientMech · CMMMech), dihydrogen (CHEBI:18276 · MediaIngredientMech · CMMMech)
Biological Processes:
- anaerobic respiration (GO:0009061 · PathwayMech)
Evidence
-
PMID:25576615 - SUPPORT (IN_VITRO)"the minimum H2 threshold value for TCE dechlorination by strain 195"
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PMID:25576615 - SUPPORT (IN_VITRO)"trichloroethene (TCE) as an electron acceptor"
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PMID:24015929 - SUPPORT (IN_VITRO)"reductive dechlorination of trichloroethene (TCE)"
Aggregation-Enhanced Hydrogen Flux
SEM directly observed joint cell aggregates during syntrophic growth. PARTIAL - a Fick diffusion model predicts that shorter interspecies distances support the hydrogen flux needed for the measured dechlorination rate. The model and microscopy do not selectively demonstrate aggregation necessity, one-way colonization facilitation or conductive electron transfer.
Participating Taxa: Dehalococcoides mccartyi 195, Syntrophomonas wolfei
Metabolites: dihydrogen (CHEBI:18276 · MediaIngredientMech · CMMMech)
Biological Processes:
- interspecies interaction between organisms (GO:0044419 · PathwayMech)
PARTIAL - aggregation could shorten diffusion distances and thereby support hydrogen delivery to strain 195 at the measured dechlorination rate. This mechanistic contribution is inferred from the diffusion model together with observed aggregates, not from selective disruption and rescue of aggregation.
Evidence
-
PMID:25576615 - SUPPORT (IN_VITRO)"Cell aggregates during syntrophic growth were observed"
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PMID:25576615 - PARTIAL (COMPUTATIONAL)"demonstrated the need for aggregation"
Associated Datasets
| Dataset | Type | Repository | Accession |
|---|---|---|---|
|
Dehalococcoides mccartyi 195 genome BioProject
NCBI BioProject for the complete genome of D. mccartyi 195, the dechlorinating partner in the coculture. |
GENOMICS | NCBI_BIOPROJECT | PRJNA214 |
|
Syntrophomonas wolfei Goettingen G311 genome BioProject
NCBI BioProject for S. wolfei subsp. wolfei strain Goettingen G311, the butyrate-fermenting syntrophic partner. |
GENOMICS | NCBI_BIOPROJECT | PRJNA13014 |
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Do aggregation and carbon-monoxide removal causally explain the coculture advantage?
The 2015 primary body supports observed aggregates and modeled hydrogen diffusion, without selective aggregation disruption. It also reports CO consumption in S. wolfei assays and lower coculture CO, proposing supplementary energy and toxicity relief; a selective exact-pair CO-removal/rescue contribution remains unresolved. New CO structure awaits one-community Edison research and primary-source assessment under #1392; this record remains needs_research. A dry run prepared the prompt, but no provider job was submitted. In the 2016 follow-up, exact-Dhc qRT-PCR is distinct from protein/complex assays with M. hungatei; induction is not genetic necessity. No figure images or supplement files were inspected.
Attaches to: ecological_interactions#Butyrate Fermentation Supporting TCE Dechlorination, ecological_interactions#Reductive Dechlorination by Dehalococcoides, ecological_interactions#Aggregation-Enhanced Hydrogen Flux
External Resources
| Name | Repository | Resource ID |
|---|---|---|
|
Exact-system primary publication - D. mccartyi 195 and S. wolfei
Primary publication describing efficient metabolic exchange and electron transfer in the D. mccartyi 195 and S. wolfei TCE-dechlorinating coculture. |
OTHER | PMID:25576615 |
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Exact-composition isotope-fractionation publication
Publication that measured TCE carbon isotope fractionation for D. mccartyi 195 with S. wolfei and other growth conditions. |
OTHER | PMID:24015929 |
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Exact-system S. wolfei reverse-electron-transfer publication
Follow-up publication measuring S. wolfei membrane complexes and gene expression in syntrophic growth with D. mccartyi strain 195. |
OTHER | doi:10.3389/fmicb.2016.01795 |
Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| TCE electron acceptor | trichloroethene | N/A |
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| Butyrate electron donor and carbon source | butyrate | N/A |
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| Low hydrogen concentration | 24 to 180 | nM |
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Growth Media
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