Chlorinated propanes, such as 1,2,3-trichloropropane (1,2,3-TCP) and 1,2-dichloropropane (1,2-DCP), have been used as solvents, degreasers, paint removers, soil fumigants, and chemical intermediates, but many of these uses have been discontinued. The United States Environmental Protection Agency classifies 1,2,3-TCP and 1,2-DCP as likely to be human carcinogens.
Under anaerobic conditions, Dehalogenimonas spp. and some Dehalococcoides strains can utilize chlorinated propanes as growth supporting electron acceptors. Lower chlorinated propanes can be degraded through aerobic cometabolism. Methanotrophs expressing soluble methane monooxygenase (sMMO) are capable of co-oxidizing 1,2-DCP, 1,3-DCP and 1,2,3-TCP. Propane oxidizing bacteria are also capable of 1,2,3-TCP cometabolism.
For more information on the molecular biological tools that can be used to assess the biodegradation of chlorinated propanes, click the section of interest in the dropdown menu below. For guidance tailored to your current needs, contact our project success team at 865-573-8188 or [email protected].
Under anaerobic conditions, Dehalogenimonas spp. and some Dehalococcoides strains are capable of utilizing chlorinated propanes as growth supporting electron acceptors. Reductive dechlorination of 1,2,3-trichloropropane (TCP) by Dehalogenimonas produces an unstable intermediate which can be hydrolyzed to form allyl alcohol or undergo reactions with sulfide-reducing agents for form allyl sulfides. In Dehalococcoides strains and Dehalogenimonas spp., 1,2-dichloropropane (DCP) undergoes dichloroelimination mediated by a dichloropropane dehalogenase to form propene.
Submit samples for CENSUS® qPCR to quantify a halorespiring bacteria and functional genes responsible for anaerobic biodegradation of DCP and TCP.
| TARGET | CODE | RELEVANCE / DATA INTERPRETATION |
|---|---|---|
| Dehalogenimonas | DHG | The Dehalogenimonas isolates characterized to date utilize a variety of vicinally chlorinated alkanes including chlorinated propanes (1,2,3-TCP and 1,2-DCP) and chlorinated ethanes (1,1,2,2-TeCA, 1,1,2-TCA, and 1,2-DCA). |
| Dehalococcoides | DHC | While the range of compounds utilized varies by strain, some Dehalococcoides strains are capable of reductive dechlorination of DCP to propene. |
| Dichloropropane Dehalogenase | 1,2-DCP | Functional gene encoding the enzyme responsible for dechlorination of 1,2-DCP. |
Although 1,3-dichloropropane (1,3-DCP) can serve as a growth supporting carbon and energy source under aerobic conditions, attempts to enrich and isolate aerobic 1,2,3-trichloropropane (TCP) and 1,2-DCP utilizing bacteria have been unsuccessful to date. Known haloalkane dehalogenase enzymes have shown little activity against chlorinated propanes.
However, chlorinated propanes can be susceptible to aerobic cometabolism. More specifically, methanotrophs expressing soluble methane monooxygenase (sMMO) are capable of co-oxidizing 1,2-DCP, 1,3-DCP and 1,2,3-TCP and cometabolism of 1,2,3-TCP has been also demonstrated for propane oxidizing bacteria. TCP cometabolism has also been observed for mixed cultures of aromatic hydrocarbon degraders that included strains utilizing toluene monooxygenase (RMO, RDEG), phenol hydroxylase (PHE) and toluene dioxygenase (TOD) pathways. However, no attempt was made to link TCP cometabolism to individual oxygenases.
CENSUS® qPCR can be performed to quantify soluble methane monooxygenase and propane monooxygenase genes.
| TARGET | CODE | RELEVANCE / DATA INTERPRETATION |
|---|---|---|
| Soluble Methane Monooxygenase | sMMO | When expressed, sMMO is capable of co-oxidation of 1,2-DCP, 1,3-DCP and 1,2,3-TCP. |
| Propane Monooxygenase | PPO | Propane oxidizing bacteria have been shown to be capable of cometabolism of TCP. |
In Situ Microcosms (ISMs) are field deployed microcosm units containing passive samplers that provide the microbial, chemical, and geochemical data for simultaneous, cost-effective evaluation of multiple remediation options.
For remedy selection at TCP and DCP impacted sites, an ISM study typically includes:
Each ISM unit contains passive samplers – passive diffusion bags (PDBs) for VOCs analysis of contaminant concentrations, passive geochem samplers for dissolved gases (ethene, ethane, methane) and anions like sulfate, and Bio-Traps® for CENSUS® qPCR quantification of Dehalogenimonas, Dehalococcoides, and DCP dehalogenase genes.
By comparing contaminant concentrations, daughter product formation, geochemical conditions, and concentrations of halorespiring bacteria between the MNA, BioStim, and BioAug units, site managers can evaluate each remediation option at a fraction of the cost of a lab bench treatability study or pilot scale study.
| REFERENCE |
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| Bosma, T, Janssen, D. Conversion of chlorinated propanes by Methylosinus trichosporium OB3b expressing soluble methane monooxygenase. Applied Microbiology and Biotechnology. 1998;50,105–112. https://doi.org/10.1007/s002530051263. |
| Martín-González L, Hatijah Mortan S, Rosell, E. Parladé M, Martínez-Alonso M, Gaju N, Caminal G, Adrian L, Marco-Urrea E. Stable carbon isotope fractionation during 1,2-dichloropropane-to-propene transformation by an enrichment culture containing Dehalogenimonas strains and a dcpA gene. Environmental Science & Technology. 2015;49, 8666-8674. https://doi.org/10.1021/acs.est.5b00929. |
| Moe WM, Yan J, Nobre MF, Costa MS da, Rainey FA. Dehalogenimonas lykanthroporepellens gen. nov., sp. nov., a reductively dehalogenating bacterium isolated from chlorinated solvent-contaminated groundwater. International Journal of Systematic and Evolutionary Microbiology. 2009;59:2692–7. https://doi.org/10.1099/ijs.0.011502-0. |
| Padilla-Crespo E, Yan J, Swift C, Wagner DD, Chourey K, Hettich RL, Ritalahti KM, Löffler FE. Identification and environmental distribution of dcpA, which encodes the reductive dehalogenase catalyzing the dichloroelimination of 1,2-dichloropropane to propene in organohalide-respiring Chloroflexi. Applied and Environmental Microbiology. 2014;80:808-818. https://doi.org/10.1128/AEM.02927-13. |
| Samin, G, Janssen, DB. Transformation and biodegradation of 1,2,3-trichloropropane (TCP). Environmental Science and Pollution Research. 2012;19:3067–3078. https://doi.org/10.1007/s11356-012-0859-3. |
| Wang B, Chu K-H. Cometabolic biodegradation of 1,2,3-trichloropropane by propane-oxidizing bacteria. Chemosphere. 2017;168:1494-1497. https://doi.org/10.1016/j.chemosphere.2016.12.007. |
| Yan J, Rash BA, Rainey FA, Moe WM. Isolation of novel bacteria within the Chloroflexi capable of reductive dechlorination of 1,2,3-trichloropropane. Environmental Microbiology. 2009;11:833-43. https://doi.org/10.1111/j.1462-2920.2008.01804.x. |