9,10-Phenanthrenedione biodegradation by a soil bacterium and identification of transformation products by LC/ESI-MS/MS

Robert A. Kanaly, Natsuko Hamamura

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10 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)1442-1449
Number of pages8
Issue number11
Publication statusPublished - Sept 2013
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Environmental Engineering
  • Environmental Chemistry
  • Chemistry(all)
  • Pollution
  • Health, Toxicology and Mutagenesis


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