Abstract

River Nile suffers from severe increase in pollutants levels due to the direct discharge of industrial effluents into its water body. So, an effort to develop active microbial strains that could be relevance in the bioremediation of these pollutants, eight fungal isolates were isolated from water samples collected from five different sites along the main stream of the River Nile in greater Cairo. Penicillium citrinum was selected as the most potent one. The fungal suspension was subjected to different durations of irradiation exposure using low power He-Ne laser (λ=632.8 nm). Irradiation for 3 minutes was the optimum activation dose. The efficiency of Penicillium citrinum in the bioremediation of paraffinic and polynuclear aromatic hydrocarbon mixtures was assessed using irradiated and non irradiated cell suspensions. On using the irradiated suspension, gas chromatographic analysis of the residual substrates indicated the degradation of 97.14% of the paraffinic hydrocarbons and 92.73% of the polynuclear aromatic hydrocarbons after 7days of incubation at 30ºC under shaking conditions (150 rpm). These results demonstrated the superiority of the irradiated fungal isolate and supported its future use in the bioremediation programs of industrial waste water.

Key words: River Nile, Penicillium citrinum, He-Ne laser irradiation, paraffinic hydrocarbons, polynuclear aromatic hydrocarbons (PAHs), gas chromatographic analysis