PLASMID-ENCODED DEGRADATION OF P-NITROPHENOL BY PSEUDOMONAS-CEPACIA

A Pseudomonas cepacia strain RKJ 200 capable of utilising p-nitropheno l (PNP+) as the sole source of carbon, nitrogen, and energy was isolat ed by selective enrichment. The degradation of PNP by this strain proc eeds through an oxidative route as indicated by the accumulation of ni trite molecules in the culture medium. Initial studies indicate that t he degradation of PNP occurs via hydroquinone as shown by thin layer c hromatography and gas chromatography studies; hydroquinone is further degraded via the beta-ketoadipate pathway. A plasmid of approximately 50 kilobase pairs was found to be responsible for carrying genes for P NP degradation in this strain. This was based on the facts that the PN P- mutants lacked the plasmid and that the PNP+ phenotype could conjug ally be transferred. In addition, the same plasmid also encoded resist ance to inorganic zinc ions. (C) 1996 Academic Press, Inc.