Regioselective oxidation of xylene isomers by Rhodococcus sp strain DK17

Abstract

Rhodococcus sp. strain DK17 is able to utilize a variety of monocyclic aromatic hydrocarbons, including benzene, phenol, toluene, and o-xylene. as growth substrates. Although DK17 is unable to grow on m- and p-xylene, this strain could transform these two xylene isomers to some extent after induction by o-xylene. The major accumulating compounds formed during the degradation of m- and p-xylene by DK17 were isolated by high-pressure liquid chromatography and identified by gas chromatography-mass spectrometric and H-1 nuclear magnetic resonance spectral techniques. Both xylene isomers were transformed to dihydroxylated compounds by what must be two successive hydroxylation events: m-xylene was converted to 2,4-dimethylresorcinol and p-xylene was converted to 2,5-dimethylhydroquinone. The rigorous structural identification of 2,4-dimethylresorcinol and 2,5-dimethylhydroquinone demonstrates that DK17 can perform distinct regioselective hydroxylations depending on the position of the substituent groups on the aromatic ring. (C) 2003 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.