The ability of the macro-fungus, Pleurotus florida, to degrade engine oil in contaminated soil was investigated with a view to ascertain its efficacy in reducing the toxicity of polluted ecosystem. Sterile soil samples (100 g) contained in polypropylene bags (12 cm diameter × 30 cm height) were contaminated with engine oil at 5, 10, 15, 20 and 25% v/w concentrations, inoculated with P. florida mycelium and incubated at 28 to 30°C for 60 days. Soil samples from the polluted soil were analyzed after the incubation period for the changes in mineral composition of the soil. At 5 and 25% engine oil concentration, all the mineral elements tested for, namely: phosphorus, magnesium, calcium and potassium showed significant changes in their composition when compared to their controls. Organic carbon increased with increasing oil concentration at 15% but later declined as the concentration of the pollutant increased from 20 to 25% engine oil concentration. The highest level of increase of carbon content was 7.07% at 15% engine oil pollution, followed by a low decrease from 6.70 to 6.48% at 20 and 25% engine oil in the soil, respectively. Statistical analysis revealed significant differences between the inoculated samples and their control, indicating degradation of the polluting oil. The results are discussed against the background of hydrocarbon pollution in the natural environment and the potentials of using P. florida in the intervention.
