Biomaterial Database

Biological reductive dechlorination of tetrachloroethylene and trichloroethylene to ethylene under methanogenic conditions. 1989

D L Freedman, and J M Gossett

School of Civil and Environmental Engineering, Cornell University, Ithaca, New York 14853-3501.

A biological process for remediation of groundwater contaminated with tetrachloroethylene (PCE) and trichloroethylene (TCE) can only be applied if the transformation products are environmentally acceptable. Studies with enrichment cultures of PCE- and TCE-degrading microorganisms provide evidence that, under methanogenic conditions, mixed cultures are able to completely dechlorinate PCE and TCE to ethylene, a product which is environmentally acceptable. Radiotracer studies with [14C]PCE indicated that [14C]ethylene was the terminal product; significant conversion to 14CO2 or 14CH4 was not observed. The rate-limiting step in the pathway appeared to be conversion of vinyl chloride to ethylene. To sustain reductive dechlorination of PCE and TCE, it was necessary to supply an electron donor; methanol was the most effective, although hydrogen, formate, acetate, and glucose also served. Studies with the inhibitor 2-bromoethanesulfonate suggested that methanogens played a key role in the observed biotransformations of PCE and TCE.

UI	MeSH Term	Description	Entries
D008697	Methane	The simplest saturated hydrocarbon. It is a colorless, flammable gas, slightly soluble in water. It is one of the chief constituents of natural gas and is formed in the decomposition of organic matter. (Grant & Hackh's Chemical Dictionary, 5th ed)
D010084	Oxidation-Reduction	A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).	Redox,Oxidation Reduction
D004579	Electron Transport	The process by which ELECTRONS are transported from a reduced substrate to molecular OXYGEN. (From Bennington, Saunders Dictionary and Encyclopedia of Laboratory Medicine and Technology, 1984, p270)	Respiratory Chain,Chain, Respiratory,Chains, Respiratory,Respiratory Chains,Transport, Electron
D005030	Ethylenes	Derivatives of ethylene, a simple organic gas of biological origin with many industrial and biological use.
D000476	Alkanesulfonates	Organic esters or salts of sulfonic acid derivatives containing an aliphatic hydrocarbon radical.	Alkyl Sulfonates,Sulfonates, Alkyl
D001673	Biodegradation, Environmental	Elimination of ENVIRONMENTAL POLLUTANTS; PESTICIDES and other waste using living organisms, usually involving intervention of environmental or sanitation engineers.	Bioremediation,Phytoremediation,Natural Attenuation, Pollution,Environmental Biodegradation,Pollution Natural Attenuation
D013750	Tetrachloroethylene	A chlorinated hydrocarbon used as an industrial solvent and cooling liquid in electrical transformers. It is a potential carcinogen.	Perchloroethylene,Perchlorethylene,Tetrachlorethylene,Tetrachloroethene
D014241	Trichloroethylene	A highly volatile inhalation anesthetic used mainly in short surgical procedures where light anesthesia with good analgesia is required. It is also used as an industrial solvent. Prolonged exposure to high concentrations of the vapor can lead to cardiotoxicity and neurological impairment.	Ethinyl Trichloride,Trichloroethene,Trielina,Trilene,Trichloride, Ethinyl
D014873	Water Pollutants	Substances or organisms which pollute the water or bodies of water. Use for water pollutants in general or those for which there is no specific heading.	Water Pollutant,Pollutant, Water,Pollutants, Water
D014874	Water Pollutants, Chemical	Chemical compounds which pollute the water of rivers, streams, lakes, the sea, reservoirs, or other bodies of water.	Chemical Water Pollutants,Landfill Leachate,Leachate, Landfill,Pollutants, Chemical Water