Fluoranthene metabolism in Mycobacterium sp. strain KR20: identity of pathway intermediates during degradation and growth

GSF – National Research Center for Environment and Health, Institute of Ecological Chemistry, Ingolstädter Landstraße 1, D-85764 Neuherberg, Germany 1 Technical University Munich, Chair of Ecological Chemistry and Environmental Analytics, D-85350 Freising, Germany 2 Author for correspondence: Klaus Rehmann. Tel: +49 89 31872514. Fax: +49 89 31873372. e-mail: rehmann{at}gsf.de Mycobacterium sp. strain KR20, which was isolated from a polycyclic aromatic hydrocarbon (PAH) contaminated soil of a former gaswork plant site, metabolized about 60% of the fluoranthene added (0·5 mg ml -1 ) to batch cultures in mineral salts medium within 10 d at 20 °C. It thereby increased its cell number about 30-fold and produced at least seven metabolites. Five metabolites, namely cis -2,3-fluoranthene dihydrodiol, Z -9-carboxymethylene-fluorene-1-carboxylic acid, cis -1,9a-dihydroxy-1-hydro-fluorene-9-one-8-carboxylic acid, 4-hydroxybenzochromene-6-one-7-carboxylic acid and benzene-1,2,3-tricarboxylic acid, could be identified by NMR and MS spectroscopic techniques and ascribed to an alternative fluoranthene degradation pathway. Besides fluoranthene, the isolate could not use any of the PAHs tested as a sole source of carbon and energy. Keywords: biodegradation, degradation products, degradation pathway, polycyclic aromatic hydrocarbons, ring cleavage Abbreviations: COSY, correlated spectroscopy; HMBC, heteronuclear multiple bond correlation; HMQC, heteronuclear multiple quantum correlation; LC, liquid chromatography; MSTFA, N -methyl- N -(trimethylsilyl) trifluoroacetamide; NOESY, nuclear Overhauser and exchange spectroscopy; PAH, polycyclic aromatic hydrocarbon; TMS, trimethylsilyl; UV-Vis, UV–visible