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Scientific classification
Domain: Bacteria
Phylum: Chloroflexi
Class: Dehalococcoidetes
Genus: Dehalococcoides
Maymo-Gatell et al. 1997

Dehalococcoides is a genus of bacteria within class Dehalococcoidetes that obtain energy via the oxidation of hydrogen gas and subsequent reductive dehalogenation of halogenated organic compounds in a mode of anaerobic respiration called dehalorespiration.[1]

Reductive dehalogenation[edit]

The first member of the "Dehalococcoides" (DHC) group, "Dehalococcoides ethenogenes", now D. mccartyi[2] strain 195 (DET) was described in 1997, and is noted for its potential use in the bioremediation of tetrachloroethene (PCE) and trichloroethene (TCE) contaminated ground water sites.[3][4] Additional DHC members were later described. These include CBDB1,[5] BAV1, VS, and GT. High DHC population numbers and electron substrate concentrations are necessary for effective bioremediation of dense non-aqueous phase liquids (DNAPL) contamination sites. Addition of either fermentable substrate to create hydrogen gas in situ, or inoculation of the site with mixed cultures containing Dehalococcoides are required for effective remediation.

Other dechlorinating microbes are also responsible for the PCE → TCE → 1,2-Dichloroethene (1,2-DCE) sequence of ethene dehalogenation,[3] but these organisms often fail to continue the degradation sequence from 1,2-DCE to vinyl chloride (VC), and finally, ethene (1,2-DCE → VC → ethene), which is environmentally benign. Dehalococcoides effectively converts 1,2-DCE to VC, and its presence in groundwater may be necessary for proper bioremediation of contaminated sites.

Mixed Dehalococcoides species can also bioremediate environmental sites contaminated with polychlorinated biphenyls (PCBs).[6]

Genome structure[edit]

Several strains of Dehalococcoides sp. has been sequenced. [7][8][9]

See also[edit]


  1. ^ See the NCBI webpage on Dehalococcoides. Data extracted from the "NCBI taxonomy resources". National Center for Biotechnology Information. Retrieved 2007-03-19. 
  2. ^ Loffler, F. E.; Yan, J.; Ritalahti, K. M.; Adrian, L.; Edwards, E. A.; Konstantinidis, K. T.; Muller, J. A.; Fullerton, H.; Zinder, S. H.; Spormann, A. M. (2012). "Dehalococcoides mccartyi gen. nov., sp. nov., obligately organohalide-respiring anaerobic bacteria relevant to halogen cycling and bioremediation, belong to a novel bacterial class, Dehalococcoidia classis nov., order Dehalococcoidales ord. nov. and family Dehalococcoidaceae fam. nov., within the phylum Chloroflexi". International Journal of Systematic and Evolutionary Microbiology. 63 (Pt 2): 625–635. ISSN 1466-5026. PMID 22544797. doi:10.1099/ijs.0.034926-0. 
  3. ^ a b Maymo-Gatell X, Chien Y, Gossett JM, Zinder SH; Chien; Gossett; Zinder (1997). "Isolation of a bacterium that reductively dechlorinates tetrachloroethene to ethene". Science. 276 (5318): 1568–1571. PMID 9171062. doi:10.1126/science.276.5318.1568. 
  4. ^ Steele, Bill (2007-06-14). "Computer modeling could help chlorine-hungry bacteria break down toxic waste". Chronicle Online. Cornell University. Retrieved 2007-11-24. 
  5. ^ Adrian L, Szewzyk U, Wecke J, Görisch H; Szewzyk; Wecke; Görisch (2000). "Bacterial dehalorespiration with chlorinated benzenes". Nature. 408 (6812): 580–583. PMID 11117744. doi:10.1038/35046063. 
  6. ^ Bedard, Donna L.; Kirsti M. Ritalahti and Frank E. Löffler (April 2007). "The Dehalococcoides Population in Sediment-Free Mixed Cultures Metabolically Dechlorinates the Commercial Polychlorinated Biphenyl Mixture Aroclor 1260" (PDF). Applied and Environmental Microbiology. 73 (8): 2513–2521. PMC 1855590Freely accessible. PMID 17308182. doi:10.1128/AEM.02909-06. 
  7. ^ Kube, M.; Beck, A.; Zinder, SH.; Kuhl, H.; Reinhardt, R.; Adrian, L. (Oct 2005). "Genome sequence of the chlorinated compound-respiring bacterium Dehalococcoides species strain CBDB1". Nat Biotechnol. 23 (10): 1269–73. PMID 16116419. doi:10.1038/nbt1131. 
  8. ^ Seshadri, R.; Adrian, L.; Fouts, DE.; Eisen, JA.; Phillippy, AM.; Methe, BA.; Ward, NL.; Nelson, WC.; et al. (Jan 2005). "Genome sequence of the PCE-dechlorinating bacterium Dehalococcoides ethenogenes". Science. 307 (5706): 105–8. PMID 15637277. doi:10.1126/science.1102226. 
  9. ^ Pöritz, M.; Goris, T.; Wubet, T.; Tarkka, MT.; Buscot, F.; Nijenhuis, I.; Lechner, U.; Adrian, L. (Jun 2013). "Genome sequences of two dehalogenation specialists – Dehalococcoides mccartyi strains BTF08 and DCMB5 enriched from the highly polluted Bitterfeld region". FEMS Microbiol Lett. 343 (2): 101–4. PMID 23600617. doi:10.1111/1574-6968.12160. 

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