Degradation of naphthalene to salicylic acid by cultures ofPseudomonas denitrificans andAchromobacter sp. from the effluents of petroleum refinery

The microbial degradation of aromatic hydrocarbons from effluents of a petroleum refinery was investigated, with emphasis on the breakdown of naphthalene to salicylic acid. The microorganisms were grown in a synthetic medium with naphthalene as the sole carbon source. The effects of pH, temperature, aeration and naphthalene concentration were studied. The optimum conditions for degradation were found to be: pH 6.0, 28°C, 25 ml medium with 1% naphthalene in 500 ml flasks. Salicylic acid was estimated by colorimetric and chromatographic methods. Maximum of growth was found on the 5th day of cultivation.Pseudomonas denitrificans produced 9.0 μg salicylic acid per ml medium,Achromobacter sp. produced 7.1 μg/ml.