p-Cymene is one of the alkyl-substituted aromatic hydrocarbons which are found in volatile oils from over 100 plants. As an initial step, Pseudomonas putida F1 degrades p-cymene by oxidizing the benzylic methyl group to yield p-cumic alcohol ([http://www.ncbi.nlm.nih.gov/pubmed/9150211|Eaton, 1997]). The p-cumic alcohol can then be further catabolised to isobutyrate, pyruvate, and acetyl-CoA by Pseudomonas putida PL ([http://www.ncbi.nlm.nih.gov/pubmed/8631713|Eaton, 1996]). Similar methyl group oxidations are found in other methyl substituted aromatic compounds including toluene, xylenes, methylnaphthalene and p-cresol. The p-cymene pathway is widespread and predominant for the degradation of para-alkyl substituted toluenes or benzoates.