Bioreduction of α,β-unsaturated ketones and aldehydes by non-conventional yeast (NCY) whole-cells

The bioreduction of alpha,beta-unsaturated ketones (ketoisophorone, 2-methyl- and 3-methyl-cyclopentenone) and aldehydes [(S)-(-)-perillaldehyde and alpha-methyl-cinnamaldehyde] by 23 non-conventional yeasts (NCYs) belonging to 21 species of the genera Candida, Cryptococcus, Debaryomyces, Hanseniaspora, Kazachstania, Kluyveromyces, Lindnera, Nakaseomyces, Vanderwaltozyma, and Wickerhamomyces was reported. The results highlight the potential of NCYs as whole-cell biocatalysts for selective biotransformation of electron-poor alkenes. A few NCYs exhibited extremely high (>90%) or even total ketoisophorone and 2-methyl-cyclopentenone bioconversion yields via asymmetric reduction of the conjugated C=C bond catalyzed by enoate reductases. Catalytic efficiency declined after switching from ketones to aldehydes. High chemoselectivity due to low competing carbonyl reductases was also sometimes observed. (C) 2010 Elsevier Ltd. All rights reserved.