Phytase activity of fungi from oil polluted soils and their ability to degrade bonnylight crude oil

Fungi were isolated from contaminated soil samples taken from three selected automobile workshops, screened for phytase activities and biodegradative abilities. Physicochemical and total petroleum hydrocarbon analyses were carried using standard chemical and gas chromatography procedures, respectively. There was significant increase (at P< or =0.05) in the potassium, sodium, calcium, magnesium, pH and organic matter of all contaminated soil samples. The fungi isolated were Aspergillus niger, Aspergillus saprophyticus, Aspergillus fumigatus, Aspergillus flavus, Trichoderma viride, Penicillium italicum, Articulospora inflata and Neurospora crassa. Of all the fungal isolates, A. flavus had the maximum phytase activity at the 48 h of incubation while N. crassa produced the least phytase activity at all the hour of incubation. Phytase activity of A. flavus and A. saprophyticus were found to be most active at pH 5.0 and 50[degrees]C. A. niger had the highest degrading ability on crude oil and spent engine oil at all days of incubation while N. crassa had the least degrading ability on crude and spent engine oil. The high total petroleum hydrocarbon (TPH) concentration in contaminated soil may be as a result of consistent exposure of the soil to spent engine oil which could make the soil conditions unsatisfactory for microbial growth.