title: Sphingomonas paucimobilis BPSI-3 mutant AN2 produces a red catabolite during biphenyl degradation.
abstract: The biphenyl degradation pathway of Sphingomonas paucimobilis BPSI-3 was investigated using a degradation-deficient mutant generated by 1-methyl-3-nitro-1-nitrosoguanidine (NTG) mutagenesis. The mutant, designated AN2, was confirmed as originating from BPSI-3 through the use of ERIC (Enterobacterial Repetitive Intergenic Consensus) PCR and by detection of the diagnostic pigment, nostoxanthin, in cellular methanol extracts. Mutant AN2 produced a yellow followed by red extracellular substance when grown in the presence of biphenyl. In the presence of 2,3-dihydroxybiphenyl, yellow followed by red then yellow compounds were formed over time. This colour change was consistent with the characteristics of a quinone, 1-phenyl-2,3-benzoquinone, which could arise from the oxidation of 2,3-dihydroxybiphenyl. A quinone was synthesised from 2,3-dihydroxybiphenyl and compared to the red compound produced by mutant AN2. Gas chromatography-mass spectrophotometry (GC-MS) confirmed that a similar quinone (4,5-dimethoxy-3-phenyl-1,2-benzoquinone) compared to the structure of the proposed biogenic compound, had been formed. This compound was also found after GC-MS analysis of mutant AN2 culture extracts. Spectrophotometric analysis of the quinone synthesised and the red product produced revealed almost identical spectral profiles. A likely inference from this evidence is that the mutant AN2 is blocked, or its activity altered, in the first gene cluster, bphA to C, of the biphenyl degradation pathway.
authors: Key Centre for Biodiversity and Bioresources, Macquarie University, Sydney 2109, Australia, and Department of Biological Sciences, Macquarie University, Sydney 2109, Australia.
authors: A D
authors: AD
authors: Davison
authors: M R
authors: MR
authors: Gillings
authors: D R
authors: DR
authors: Jardine
authors: P
authors: P
authors: Karuso
authors: A S
authors: AS
authors: Nouwens
authors: J J
authors: JJ
authors: French
authors: D A
authors: DA
authors: Veal
authors: N
authors: N
authors: Altavilla