Degradation of 4-nitrocatechol by Burkholderia cepacia: a plasmid-encoded novel pathway

Pseudomonas cepacia RKJ200 (non described as Buckholderia cepacia) has been shown to utilize p-nitrophenol (PNP) as sole carbon and energy source. The present work demonstrates that RKJ200 utilizes 4-nitrocatechol (NC) as the sole source of carbon, nitrogen and energy, and is degraded with concomita nt release of nitrite ions. Several lines of evidence, including thin layer chromatography, gas chromatography, H-1-nuclear magnetic resonance, gas ch romatography-mass spectrometry; spectral analyses and quantification of int ermediates by high performance liquid chromatography, have shown that NC is degraded via 1,2,4-benzenetriol (BT) and hydroquinone (HQ) formation. Stud ies carried out on a PNP- derivative and a PNP+ transconjugant also demonst rate that the genes for the NC degradative pathway reside on the plasmid pr esent in RKJ200; the same plasmid had earlier been shown to encode genes fo r PNP degradation, which is also degraded via HQ formation. It is likely, t herefore, that the same sets of genes encode the further metabolism of HQ i n NC and PNP degradation.