Dehalorespiration

Attention is drawn to the dechlorination by anaerobic bacteria of both chlorinated ethenes and chlorophenolic compounds that serve as electron acceptors with electron donors including formate, pyruvate, and acetate. This is termed dehalorespiration and is important in the degradation of a range of halogenated compounds under anaerobic conditions, and is discussed further in Chapter 3, Part 2 and Chapter 7, Part 3. 

Reduction in which a halogen atom is replaced by hydrogen including dehalorespiration... 

Drzyzga O, JC Gottschal (2002) Tetrachloroethene dehalorespiration and growth of Desulfitobacteriumfrap-pieri TCEl in strict dependence on the activity of Desulfovibriofructosivorans. Appl Environ Microbiol 68 542-549. 

Sun B, BM Griffin, HL Ayala-delRio, SA Hashsham, JM Tiedje (2002) Microbial dehalorespiration with 1,1,1-trichloroethane. Science 298 1023-1025. 

Attention has been directed to the dechlorination of polychlorinated benzenes by strains that use them as an energy source by dehalorespiration. Investigations using Dahalococcoides sp. strain CBDBl have shown its ability to dechlorinate congeners with three or more chlorine substituents (Holscher et al. 2003). Although there are minor pathways, the major one for hexachlorobenzene was successive reductive dechlorination to pentachlorobenzene, 1,2,4,5-tetrachlorobenzene, 1,2,4-trichlorobenzene, and 1,4-dichlorobenzene (Jayachandran et al. 2003). The electron transport system has been examined by the use of specific inhibitors. lonophores had no effect on dechlorination, whereas the ATP-synthase inhibitor A,A -dicyclohexylcarbodiimide (DCCD) was strongly inhibitory (Jayachandran et al. 2004). 

Jayachandran G, H Gorisch, L Adrian (2003) Dehalorespiration with hexachlorobenzene and pentachloroben-zene by Dehalococcoides sp. strain CBDBl. Arch Microbiol 180 411-416. 

Louie TM, WW Mohn (1999) Evidence for a chemiosmotic model of dehalorespiration in Desulfomonile tiedjei DCB-1. J Bacterial 181 40-46. 

The partial anaerobic dechlorination of pentachloropyridine to a trichloropyridine of unestablished orientation by the dehalorespiring Desulfitobacterium hafniense (frappieri) PCP-1 has been demonstrated (Dennie et al. 1998). 

In dehalogenating enzymes of anaerobic microorganisms, corrinoid cofactors have a newly discovered further role in the redox catalysis of the energy conserving dehalogenation of chloro(hydro)carbon compounds ( dehalorespiration ), and the specific redox properties of the protein-bound unusual corrinoids are of particular current interest. 

Reductive respiration is associated mostly with halogen derivatives hydrocarbons, which are used as acceptors of electrons. Due to this, the process is also called dehalorespiration or simply halorespiration. Ihe electron donor here is directly dissolved H. Its necessary amount is provided by the fermentation. That is why halorespiration and dechlorination run in two steps (Wiedemeier et al, 1999). Initially H formsin the process of fermentation of non-chlorinated organic compoimds and then it is used as electron donor ... 

Adrian, L., Szewzyk, U., Wecker, J., Giorisch, H. Bacterial dehalorespiration witli chlorinated benzenes. Nature 2000,480, 580-583. 

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