Bacterial Cycling of Methyl Halides

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This chapter focuses on the monohalogenated methanes methyl chloride (MeCl) and methyl bromide (MeBr), their natural and anthropogenic sources, and their degradation by microorganisms, specifically by aerobic bacteria that can use MeBr and MeCl as sole source of carbon and energy. The biogeochemical cycle of methyl halides and the microbiology, biochemistry, genetics, and biotechnological potential of methyl halide-degrading microorganisms are discussed in the chapter. Methyl halides are the dominant halocarbons in the atmosphere. They play an important role in regulating stratospheric ozoneconcentrations and global warming as well, two factors governing planetary habitability. The monohalomethanes—methyl chloride (MeCl), methyl bromide (MeBr), and methyl iodide (MeI)—are trace gases in the atmosphere with average tropospheric-mixing ratios of 600, 10, and 2 parts per trillion (ppt), respectively. However, methyl halides are radiatively active and hence contribute to global warming by absorbing radiation in the infrared region. This is evident in their elevated global warming potential (GWP), a value calculated to quantify each compound's warming effect (on a mass basis) relative to the same mass of CO2. Compounds with high GWP including those like methyl halides with low concentrations may have considerable impact on atmospheric warming when compared with other “greenhouse” gases with low GWP.

Additional publication details

Publication type Book chapter
Publication Subtype Book Chapter
Title Bacterial Cycling of Methyl Halides
DOI 10.1016/S0065-2164(06)61009-5
Volume 61
Year Published 2007
Language English
Publisher Elsevier
Contributing office(s) National Research Program - Western Branch, Toxic Substances Hydrology Program
Description 40 p.
Larger Work Type Book
Larger Work Title Advances in Applied Microbiology
First page 307
Last page 346