Menthol is a monoterpene found in many essential oils, including spearmint and peppermint. It is widely used in commercial products such as toothpaste, mouthwashes, cigarettes, foods, and medicines ([http://www.ncbi.nlm.nih.gov/pubmed/10460066|Gelal et al., 1999]). In 1984, world production of this popular compound was estimated to be 3500 tons. Thauera terpenica strain 21Mol is able to grow on (-)-menthol, as well as on (-)-menthone, (+)-isomenthol, (+)-isopulegol, and (+)-pulegone [http://www.ncbi.nlm.nih.gov/pubmed/9841126|(Foss and Harder, 1998)]. Based on the bacterium`s apparent requirement for an oxygen functional group at the C-3 atom, [http://www.ncbi.nlm.nih.gov/pubmed/9990726|Hylemon and Harder (1998)] suggest that the menthol degradation pathway resembles the anaerobic oxidation and cleavage of cyclohexanol described by [http://www.ncbi.nlm.nih.gov/pubmed/2505723|Dangel et al. (1989)]. In this proposed pathway, menthol and the related substrates listed above are first converted to menth-2-enone, which is then oxidized to mentha-1,2-dione. This compound may then be attacked by HSCoA to produce 3,7-dimethyl-5-oxo-octyl-CoA, which in turn may be degraded on Seubert`s pathway ([http://www.ncbi.nlm.nih.gov/pubmed/9990726|Hylemon and Harder, 1998]).