Abstract

Phenol is a very toxic substance and it can cause a number of environmental problems when it enters a water system.  Biological treatment is considered a cost-effective and safe technology and it plays an important role in the remediation of environmental pollutants. In this study, Pseudomonas fluorescens ATCC 948 and Pseudomonas putida ATCC 12842 were employed to biodegrade phenol, with different culture conditions such as, different incubation periods, initial phenol concentration, temperature, pH, carbon and nitrogen sources) used to examine their effect on phenol degradation. The results showed that phenol degraded completely after 122 h. Different initial concentrations of phenol were added to minimal salts medium and the percentage of phenol degradation decreased as the phenol concentration increased. The optimum temperature for both bacterial strains, P. fluorescens and P. putida, is 35°C, with the maximum percentage of degradation occuring at pH 7. Glucose is the best carbon source as it increased the rate of biodegradation up to 80%. Ammonium nitrate is the best nitrogen source for P. fluorescens to degrade phenol, while ammonium chloride is the best source of nitrogen for degradation of phenol by P. putida. The study’s results suggest that P. fluorescens and P. putida are capable of phenol degradation, and thus can be used for bioremediation of synthetic waste water containing phenol.

Key words: Physicochemical factors, biodegradation, Pseudomonas fluorescens, Pseudomonas putida.