Propanotrophic Chlorinated Ethene Cometabolism Enrichment Cultures

Community ID CommunityMech:000271

Ecological State ENGINEERED

Environment aerobic propane-amended chlorinated-ethene enrichment culture
ENVO:01001405

Propane-enriched aerobic mixed cultures derived from three Michigan State University Long-Term Ecological Research agricultural soils (Soils T2, T3, T4) and from impacted-site sediment at a West Coast Naval Station (Site 1), evaluated for cometabolic biodegradation of three chlorinated ethenes - trichloroethene (TCE), cis-1,2-dichloroethene (cDCE), and 1,1-dichloroethene (1,1-DCE) - in the presence of propane as growth substrate. Substrate-specific selection drove distinct dominance patterns: cDCE-amended cultures were dominated by Mycolicibacterium followed by Mycobacterium, TCE-amended cultures were dominated by Rhodococcus (R. opacus or R. wratislaviensis from agricultural soils; Mycolicibacterium/Mycobacterium/Rhodococcus mixture from the impacted site sediment), and the subset of 1,1-DCE-degrading cultures was dominated by Pseudonocardia (with a truncated propane monooxygenase alpha subunit suggesting alternative enzymes drive 1,1-DCE transformation). The enrichments express group 5 (prmABCD) and putative group 6 propane monooxygenases. The system supports development of propane-based bioaugmentation strategies for mixed chlorinated solvent contamination under aerobic conditions.

Taxonomy

Taxon	Ontology ID	Functional Roles	Abundance
Rhodococcus opacus	NCBITaxon:37919	PRIMARY_DEGRADER	DOMINANT
doi:10.1016/j.jenvman.2026.129957 - SUPPORT (COMPUTATIONAL) "Rhodococcus metagenome-assembled genomes (MAGs) in the TCE degrading cultures classified as R. opacus or R. wratislaviensis"
Rhodococcus wratislaviensis	NCBITaxon:44752	PRIMARY_DEGRADER	DOMINANT
doi:10.1016/j.jenvman.2026.129957 - SUPPORT (COMPUTATIONAL) "Rhodococcus metagenome-assembled genomes (MAGs) in the TCE degrading cultures classified as R. opacus or R. wratislaviensis"
Mycolicibacterium	NCBITaxon:1866885	PRIMARY_DEGRADER	DOMINANT
doi:10.1016/j.jenvman.2026.129957 - SUPPORT (COMPUTATIONAL) "cDCE-degrading cultures being dominated by Mycobacterium and Mycolicibacterium"
Mycobacterium	NCBITaxon:1763	PRIMARY_DEGRADER	COMMON
doi:10.1016/j.jenvman.2026.129957 - SUPPORT (COMPUTATIONAL) "cDCE-degrading cultures being dominated by Mycobacterium and Mycolicibacterium"
Pseudonocardia	NCBITaxon:1847	PRIMARY_DEGRADER	DOMINANT
doi:10.1016/j.jenvman.2026.129957 - PARTIAL (COMPUTATIONAL) "1,1-DCE degrading cultures were dominated by Pseudonocardia, although the associated MAGs contained a truncated propane monooxygenase alpha subunit, suggesting other enzymes were responsible for 1,1-DCE transformation"
Pseudonocardia broussonetiae	NCBITaxon:2736640	PRIMARY_DEGRADER	COMMON
doi:10.1016/j.jenvman.2026.129957 - SUPPORT (COMPUTATIONAL) "two classified as Pseudonocardia broussonetiae (only from the impacted site enrichments)"
Methylibium	NCBITaxon:316612	CROSS_FEEDER	RARE
doi:10.1016/j.jenvman.2026.129957 - SUPPORT (COMPUTATIONAL) "Two MAGs, from soil T3 and T4 cDCE amended enrichments, classified within the phylum Proteobacteria (Methylibium and an unclassified Burkholderiaceae)"
unclassified Burkholderiaceae	NCBITaxon:119060	CROSS_FEEDER	RARE
doi:10.1016/j.jenvman.2026.129957 - SUPPORT (COMPUTATIONAL) "Two MAGs, from soil T3 and T4 cDCE amended enrichments, classified within the phylum Proteobacteria (Methylibium and an unclassified Burkholderiaceae)"

Ecological Interactions

Taxon

Cross-feeding

Mutualism

Syntrophy

Competition

Commensalism

Niche partitioning

Colonization facilitation

Strain competition

Predation

Propane-Cometabolic TCE Degradation by Rhodococcus

CROSS_FEEDING

Source Taxon: Rhodococcus opacus

Metabolites: trichloroethene (CHEBI:16602), propane (CHEBI:32879)

Biological Processes:

cellular response to xenobiotic stimulus (GO:0071466)

Evidence

doi:10.1016/j.jenvman.2026.129957 - SUPPORT (IN_VITRO)

"TCE-degrading cultures were dominated by Rhodococcus"
doi:10.1016/j.jenvman.2026.129957 - SUPPORT (COMPUTATIONAL)

"Functional gene analysis identified both group 5 (prmABCD) and putative group 6 propane monooxygenases"

Propane-Cometabolic cDCE Degradation by Mycolicibacterium and Mycobacterium

CROSS_FEEDING

Source Taxon: Mycolicibacterium

Metabolites: cis-1,2-dichloroethene (CHEBI:18882), propane (CHEBI:32879)

Biological Processes:

cellular response to xenobiotic stimulus (GO:0071466)

Evidence

doi:10.1016/j.jenvman.2026.129957 - SUPPORT (IN_VITRO)

"cDCE-degrading cultures being dominated by Mycobacterium and Mycolicibacterium"
doi:10.1016/j.jenvman.2026.129957 - PARTIAL (COMPUTATIONAL)

"the order would be prmACDB, an order previously been reported for propane monooxygenase operons in other Mycobacterium strains"

Substrate-Specific Selection Across Chlorinated Ethenes

COMPETITION

Metabolites: trichloroethene (CHEBI:16602), cis-1,2-dichloroethene (CHEBI:18882), 1,1-dichloroethene (CHEBI:34031)

Biological Processes:

response to xenobiotic stimulus (GO:0009410)

Evidence

doi:10.1016/j.jenvman.2026.129957 - SUPPORT (IN_VITRO)

"Whole genome sequencing analyses revealed pronounced substrate-dependent selection of microbial communities"
doi:10.1016/j.jenvman.2026.129957 - SUPPORT (IN_VITRO)

"substrate-specific pressures govern propanotrophic community structure and function, and highlight distinct roles of key actinobacterial genera in chlorinated ethene cometabolism"

1,1-DCE-Driven Inhibition of Propanotrophs

COMPETITION

Metabolites: 1,1-dichloroethene (CHEBI:34031), propane (CHEBI:32879)

Biological Processes:

response to xenobiotic stimulus (GO:0009410)

Evidence

doi:10.1016/j.jenvman.2026.129957 - SUPPORT (IN_VITRO)

"1,1-DCE removal was absent at elevated concentrations, both trends consistent with inhibitory or toxic effects"

External Resources

Name	Repository	Resource ID
Primary publication PDF Faghihinezhad, Eshghdoostkhatami, Cupples 2026 Journal of Environmental Management - "Characterization of multiple trichloroethene, cis-dichloroethene and 1,1-dichloroethene degrading propanotrophic communities". Local PDF copy at references_pdfs/Faghihinezhad_2026_propanotrophic_TCE_cDCE_DCE.pdf.	OTHER	doi:10.1016/j.jenvman.2026.129957
doi:10.1016/j.jenvman.2026.129957 - SUPPORT (IN_VITRO) "substrate-specific pressures govern propanotrophic community structure and function"

Environmental Factors

Factor	Value	Unit
Propane as growth substrate	0.8-1.2 mg/L per amendment	N/A
doi:10.1016/j.jenvman.2026.129957 - SUPPORT (IN_VITRO) "propane-enriched mixed cultures (derived from agricultural soils and an impacted site sediment)"
Chlorinated ethene contaminant concentration	TCE and cDCE at 4-5 mg/L; 1,1-DCE at 0.5-1 mg/L	N/A
doi:10.1016/j.jenvman.2026.129957 - SUPPORT (IN_VITRO) "TCE (4 to 5 mg/L), cDCE (4 to 5 mg/L) and 1,1-DCE (0.5 to 1 mg/L) were added to the active microcosms and abiotic controls"
Inoculum source	KBS-LTER agricultural soils T2/T3/T4 + West Coast Naval Station Site 1 sediment	N/A
doi:10.1016/j.jenvman.2026.129957 - SUPPORT (IN_VITRO) "The propanotropic enrichment cultures were developed from a previous study examining the biodegradation of 1,4-dioxane using inocula from various sources (three agricultural soils, impacted site sediment)"
Aerobic incubation	orbital shaker at 120 rpm, room temperature	N/A
doi:10.1016/j.jenvman.2026.129957 - SUPPORT (IN_VITRO) "All microcosms were incubated at room temperature on an orbital shaker operated at 120 rpm"

Growth Media

mineral salts medium (phosphate buffer plus trace-metal stock; K2HPO4/KH2PO4/NH4Cl with MgSO4, FeSO4, MnSO4, ZnSO4, CoCl2)

pH 7.4

Temperature room temperature °C

Atmosphere AEROBIC

Preparation notes: Propane supplied as the sole carbon and energy source in the headspace; serial transfers (10 mL culture into 20 mL fresh medium; dilution ratio changed from 1:9 to 1:2).

Evidence

doi:10.1016/j.jenvman.2026.129957

"consisted of 160 mL serum bottles containing 10 g (wet weight) of soil or sediment and 30 mL of liquid media, with the remaining volume serving as the gas headspace"

doi:10.1016/j.jenvman.2026.129957

"All microcosms were incubated at room temperature on an orbital shaker operated at 120 rpm"

doi:10.1016/j.jenvman.2026.129957

"The solution pH was then adjusted to 7.4 and placed in the autoclave for sterilization"