Degradation of o-nitrophenol and m-nitrophenol by a Pseudomonas putida

A Pseudomonas putida strain that grew on o-nitrophenol (ONP) and m-nitrophenol (MNP) as sole sources of carbon and nitrogen was isolated from soil. The microorganism was unable to metabolize p-nitrophenol. Growing and resting cells of P. putida degraded ONP releasing nitrite and MNP releasing ammonium. Enzymes involved in the metabolism of ONP or MNP were inducible by ONP or MNP, respectively. ONP was degradable in a cell-free system. The initial enzyme converted ONP to catechol and nitrite. The enzyme required NADPH as a coenzyme and its specific activity was 15 mu mol min super(-1) (g of protein) super(-1).