title: 9,10-Phenanthrenedione biodegradation by a soil bacterium and identification of transformation products by LC/ESI-MS/MS.
abstract: Transformation of 9,10-phenanthrenedione, a cytotoxic derivative of phenanthrene, was shown to occur by a soil bacterium belonging to the genus Sphingobium. Phenanthrene-grown cells of this strain were exposed to 50mgL(-1) 9,10-phenanthrenedione in liquid cultures, extracted, and extracts were analyzed by liquid chromatography electrospray ionization mass spectrometry in negative ionization mode. Full scan analyses of exposed cells over the range from m/z 50 to m/z 500 were compared to abiotic and biotic controls. Product and precursor ion scan mode analyses indicated that at least three aromatic ring-cleavage transformation products of 9,10-phenanthrenedione were present and structures for these products, corresponding to [M-H](-)=271, [M-H](-)=241, and [M-H](-)=339 were proposed to be 4-(1-hydroxy-3,4-dioxo-2-naphthyl)-2-oxo-but-3-enoic acid, 2,2'-diphenic acid and 2-[(6-carboxy-2,3-dihydroxy-phenyl)-hydroxy-methyl]-5-oxo-hex-3-enedioic acid. The identity of 2,2'-diphenic acid was confirmed by comparison to an authentic standard and when the strain was exposed to 50mgL(-1) 2,2'-diphenic acid in separate assays, a transformation product with a similar mass spectrum as 9,10-phenanthrenedione-derived [M-H](-)=339 was revealed. Based upon these results, pathways for the transformation of 9,10-phenanthrenedione by strain KK22 were proposed. Strain KK22 appeared unable to use 9,10-phenanthrenedione as a growth substrate under these conditions. This is the first report of potential biotransformation pathways of 9,10-phenanthrenedione by a bacterium.
authors.affiliation: Department of Genome System Science, Faculty of Bionanosciences, Yokohama City University, Yokohama 236-0027, Japan. kanaly@yokohama-cu.ac.jp
authors.forename: Robert A
authors.initials: RA
authors.lastname: Kanaly
authors.forename: Natsuko
authors.initials: N
authors.lastname: Hamamura
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D001673:Biodegradation, Environmental; D001713:Biphenyl Compounds / Q000302:isolation & purification / Q000378:metabolism; D002853:Chromatography, Liquid; D004785:Environmental Pollutants / Q000302:isolation & purification / Q000378:metabolism*; D010616:Phenanthrenes / Q000302:isolation & purification / Q000378:metabolism*; D012988:Soil Microbiology; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry
chemical_list: D001713:Biphenyl Compounds; D004785:Environmental Pollutants; D010616:Phenanthrenes; C005399:9,10-phenanthrenequinone; C039204:diphenic acid
keywords: 9,10-Phenanthrenedione; Biotransformation; LC/ESI-MS/MS; PAH o-quinones; Soil bacterium