Related Experiment Video
Updated: Jun 1, 2026

Development of Sulfidogenic Sludge from Marine Sediments and Trichloroethylene Reduction in an Upflow Anaerobic Sludge Blanket Reactor
Published on: October 15, 2015
Identification and characterisation of an elusive bacterial enzyme system for chloromethane dehalogenation
Jasmin Bernhardt1,2,3, Lukas K R Hofmann1,2,3,4, Paul Klemm5
1Institute for Molecular Microbiology and Biotechnology, University of Münster, Münster, Germany.
Abstract:
Chloromethane, a toxic gas primarily produced naturally, contributes to stratospheric ozone destruction. The anaerobic acetogen Acetobacterium dehalogenans can utilise chloromethane as a carbon and energy source, but the associated dehalogenase/methyltransferase has remained elusive. Through comparative transcriptomics we identify a gene cluster, cdmBCA, which encodes a corrinoid-dependent methyltransferase system distinct from the characterised Cmu system used for chloromethane degradation in aerobic methylotrophs. Biochemical characterisation reveals that the Cdm system reacts with other haloalkanes, but not with methoxylated aromatics, unlike closely related O-demethylases. X-ray structural analysis of the protein CdmB shows a hydrophobic channelling system directing haloalkanes towards cobalamin-dependent activation. Homologous proteins are found in anaerobic prokaryotes, particularly within the phyla Bacillota and Asgardarchaeota, suggesting previously unidentified microbial transformation of chloromethane in the environment. Discovery of the Cdm dehalogenation/methyltransferase system sheds light on the microbial contribution to the global chloromethane cycle.
Related Concept Videos
Microbial Bioremediation of Pesticides
Radical Substitution: Halogenation of Alkanes and Alkyl Substituents
In the initiation step of the reaction, the chlorine molecule undergoes homolytic cleavage in the presence of light or heat, forming two highly reactive chlorine radicals. Propagation occurs in two...
Halogenation of Alkenes
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
E1 Reaction: Kinetics and Mechanism
Multiple Halogenation of Methyl Ketones: Haloform Reaction
Reactions at the Benzylic Position: Halogenation

