title: Biotransformation of the high-molecular weight polycyclic aromatic hydrocarbon (PAH) benzo[k]fluoranthene by Sphingobium sp. strain KK22 and identification of new products of non-alternant PAH biodegradation by liquid chromatography electrospray ionization tandem mass spectrometry.
abstract: A pathway for the biotransformation of the environmental pollutant and high-molecular weight polycyclic aromatic hydrocarbon (PAH) benzo[k]fluoranthene by a soil bacterium was constructed through analyses of results from liquid chromatography negative electrospray ionization tandem mass spectrometry (LC/ESI(-)-MS/MS). Exposure of Sphingobium sp. strain KK22 to benzo[k]fluoranthene resulted in transformation to four-, three- and two-aromatic ring products. The structurally similar four- and three-ring non-alternant PAHs fluoranthene and acenaphthylene were also biotransformed by strain KK22, and LC/ESI(-)-MS/MS analyses of these products confirmed the lower biotransformation pathway proposed for benzo[k]fluoranthene. In all, seven products from benzo[k]fluoranthene and seven products from fluoranthene were revealed and included previously unreported products from both PAHs. Benzo[k]fluoranthene biotransformation proceeded through ortho-cleavage of 8,9-dihydroxy-benzo[k]fluoranthene to 8-carboxyfluoranthenyl-9-propenic acid and 9-hydroxy-fluoranthene-8-carboxylic acid, and was followed by meta-cleavage to produce 3-(2-formylacenaphthylen-1-yl)-2-hydroxy-prop-2-enoic acid. The fluoranthene pathway converged with the benzo[k]fluoranthene pathway through detection of the three-ring product, 2-formylacenaphthylene-1-carboxylic acid. Production of key downstream metabolites, 1,8-naphthalic anhydride and 1-naphthoic acid from benzo[k]fluoranthene, fluoranthene and acenaphthylene biotransformations provided evidence for a common pathway by strain KK22 for all three PAHs through acenaphthoquinone. Quantitative analysis of benzo[k]fluoranthene biotransformation by strain KK22 confirmed biodegradation. This is the first pathway proposed for the biotransformation of benzo[k]fluoranthene by a bacterium.
authors: Department of Life and Environmental System Science, Graduate School of Nanobiosciences, Yokohama City University, 22-2 Seto, Kanazawa, Yokohama, 236-0027, Japan.
authors: Allyn H
authors: AH
authors: Maeda
authors: Shinro
authors: S
authors: Nishi
authors: Yuji
authors: Y
authors: Hatada
authors: Yasuhiro
authors: Y
authors: Ozeki
authors: Robert A
authors: RA
authors: Kanaly
mesh_terms: D000073:Acenaphthenes / Q000378:metabolism; D001711:Biotransformation; D002853:Chromatography, Liquid; D005449:Fluorenes / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D011084:Polycyclic Aromatic Hydrocarbons / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization; D042301:Sphingomonadaceae / Q000378:metabolism*; D053719:Tandem Mass Spectrometry
chemical_list: D000073:Acenaphthenes; D005449:Fluorenes; D011084:Polycyclic Aromatic Hydrocarbons; C042553:acenaphthylene; C007738:fluoranthene; C022921:benzo(k)fluoranthene