Biodegradation

, Volume 5, Issue 3–4, pp 237–248

Microbes, enzymes and genes involved in dichloromethane utilization

  • Thomas Leisinger
  • Regula Bader
  • René Hermann
  • Monika Schmid-Appert
  • Stéphane Vuilleumier
Article

DOI: 10.1007/BF00696462

Cite this article as:
Leisinger, T., Bader, R., Hermann, R. et al. Biodegradation (1994) 5: 237. doi:10.1007/BF00696462

Abstract

Dichloromethane (DCM) is efficiently utilized as a carbon and energy source by aerobic, Gram-negative, facultative methylotrophic bacteria. It also serves as a sole carbon and energy source for a nitrate-respiringHyphomicrobium sp. and for a strictly anaerobic co-culture of a DCM-fermenting bacterium and an acetogen. The first step of DCM utilization by methylotrophs is catalyzed by DCM dehalogenase which, in a glutathione-dependent substitution reaction, forms inorganic chloride and S-chloromethyl glutathione. This unstable intermediate decomposes to glutathione, inorganic chloride and formaldehyde, a central metabolite of methylotrophic growth. Genetic studies on DCM utilization are beginning to shed some light on questions pertaining to the evolution of DCM dehalogenases and on the regulation of DCM dehalogenase expression. DCM dehalogenase belongs to the glutathione S-transferase supergene family. Analysis of the amino acid sequences of two bacterial DCM dehalogenases reveals 56% identity, and comparison of these sequences to those of glutathione S-transferases indicates a closer relationship to class Theta eukaryotic glutathione S-transferases than to a number of bacterial glutathione S-transferases whose sequences have recently become available.dcmA, the structural gene of the highly substrate-inducible DCM dehalogenase, is carried in most DCM utilizing methylotrophs on large plasmids. InMethylobacterium sp. DM4 its expression is governed bydcmR, a regulatory gene located upstream ofdcmA. dcmR encodes atrans-acting factor which negatively controls DCM dehalogenase formation at the transcriptional level. Our working model thus assumes that thedcmR product is a repressor which, in the absence of DCM, binds to the promoter region ofdcmA and thereby inhibits initiation of transcription.

Key words

Dichloromethane dichloromethane dehalogenase glutathione S-transferase methylotrophic bacteria Methylobacterium sp. Methylophilus sp. 

Copyright information

© Kluwer Academic Publishers 1994

Authors and Affiliations

  • Thomas Leisinger
    • 1
  • Regula Bader
    • 1
  • René Hermann
    • 1
  • Monika Schmid-Appert
    • 1
  • Stéphane Vuilleumier
    • 1
  1. 1.Mikrobiologisches Institut ETH, ETH-ZentrumZürichSwitzerland

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