Benz[a]anthracene Biotransformation and Production of Ring Fission Products by Sphingobium sp. Strain KK22 |
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Authors: | Marie Kunihiro Yasuhiro Ozeki Yuichi Nogi Natsuko Hamamura Robert A Kanaly |
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Institution: | Department of Life and Environmental System Science, Graduate School of Nanobiosciences, Yokohama City University, Kanazawa, Kanagawa, Yokohama, Japana;Extremobiosphere Research Program, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japanb;Center for Marine Environmental Studies, Ehime University, Matsuyama, Japanc |
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Abstract: | A soil bacterium, designated strain KK22, was isolated from a phenanthrene enrichment culture of a bacterial consortium that grew on diesel fuel, and it was found to biotransform the persistent environmental pollutant and high-molecular-weight polycyclic aromatic hydrocarbon (PAH) benza]anthracene. Nearly complete sequencing of the 16S rRNA gene of strain KK22 and phylogenetic analysis revealed that this organism is a new member of the genus Sphingobium. An 8-day time course study that consisted of whole-culture extractions followed by high-performance liquid chromatography (HPLC) analyses with fluorescence detection showed that 80 to 90% biodegradation of 2.5 mg liter−1 benza]anthracene had occurred. Biodegradation assays where benza]anthracene was supplied in crystalline form (100 mg liter−1) confirmed biodegradation and showed that strain KK22 cells precultured on glucose were equally capable of benza]anthracene biotransformation when precultured on glucose plus phenanthrene. Analyses of organic extracts from benza]anthracene biodegradation by liquid chromatography negative electrospray ionization tandem mass spectrometry LC/ESI(−)-MS/MS] revealed 10 products, including two o-hydroxypolyaromatic acids and two hydroxy-naphthoic acids. 1-Hydroxy-2- and 2-hydroxy-3-naphthoic acids were unambiguously identified, and this indicated that oxidation of the benza]anthracene molecule occurred via both the linear kata and angular kata ends of the molecule. Other two- and single-aromatic-ring metabolites were also documented, including 3-(2-carboxyvinyl)naphthalene-2-carboxylic acid and salicylic acid, and the proposed pathways for benza]anthracene biotransformation by a bacterium were extended. |
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