Overview of the biotransformation reactions of monoterpene alcohols and esters catalyzed by lager, ale and non-conventional yeasts and proposed transformation of myrcene from bacterial studies. The enzymatic reaction carried out by Oye2 has been experimentally verified in S. cerevisiae and is indicated in green, putative enzymatic activities that have been implied from metabolite profiling in fermentations with Saccharomyces yeast (King and Dickinson 2000, 2003) are indicated in blue, and reactions in Castellaniella defragrans and Pseudomonas aeruginosa that have not yet been demonstrated in yeast (Brodkorb et al.2010; Esmaeili and Hashemi 2011) are indicated in orange. The monoterpenoids can also be acetylated by Atf1/2 via their functional group, which is not indicated in the figure. CL, cyclase; DH, dehydrogenase; DT, dehydratase; IS, isomerase; HL, hydroxylase.