Sunday, June 3, 2012

A bacterium named after chemical transformations that it supports: Dehalococcoides ethenogenes

Dehalococcoides ethenogenes is an anaerobic, Gram-positive bacterium (phylum: Chloroflexi, class: Dehalococcoidetes)  [1].  Its name, Dehalococcoides ethenogenes, hints at the chemical transformations that it can perform: dehalogenation of halogenated ethene compounds to ethene.

Halogenated solvents such as chlorinated ethenes are environmental pollutants, often with a characteristic of long-term persistence. The discovery that D. ethenogenes can help to convert toxic chemicals into less harmful ones is of interest for the treatment of soil and groundwater, when contaminated with such halogenated hydrocarbons. It has been demonstrated, for example, that D. ethenogenes (strain 195)—transferred into an optimized growth medium—completely decomposes tetrachloroethene by reductive dechlorination [2,3].

An interesting question is if D. ethenogenes evolved in contaminated soil environments and developed the metabolic capability to transform chlorinated hydrocarbons for its own benefit. If so, this would be an example for “natural selection on speed” [4].

Keywords: microbiology, bioremediation, metabolic pathway, reductive dehalogenation, terminology.

References and more to explore
[1] Microbe Wiki: Dehalococcoides ethenogenes [].
[2] X. Maymó-Gatell, Y.-t. Chien, J. M. Gossett and S. H. Zinder: Isolation of a Bacterium That Reductively Dechlorinates Tetrachloroethene to Ethene. Science 1997, 276 (5318), pp. 1568-1571. DOI: 10.1126/science.276.5318.1568
[3] X. Maymó-Gatell, T. Anguish and S. H. Zinder: Reductive Dechlorination of Chlorinated Ethenes and 1,2-Dichloroethane by “Dehalococcoides ethenogenes” 195. Applied and Environmental Microbiology 1999, 65 (7), pp. 3108-3113 [].
[4] Tim Friend: The Third Domain. The Untold Story of Archaea and the Future of Biotechnology. Joseph Henry Press, Washington, D.C., 2007; page 248.

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