Enhancing the Performance of Three White-rot Fungi in the Mycoremediation of Crude Oil Contaminated Soil

Contamination of soils by petroleum hydrocarbon is on the increase, particularly in the oil producing areas of Nigeria. White-rot fungi have enzymes which are capable of turning these organic compounds into harmless substances. This work investigated the performance of three white-rot fungi (Pleurotus tuber-regium, P. ostreatus and P. pulmonarius) for the remediation of different concentrations (0, 1, 2.5, 5, 10 and 20% w/v) of crude oil contaminated soils with sawdust and poultry manure as bedding materials. Ten grammes of each of the white-rot fungi were separately inoculated in each bottle containing exhaustively cropped topsoil (200 g), rice straw (40 g) and wheat bran (20 g). Each treatment was conducted in three replicates and arranged in a 3 x 6 x 3 complete randomised design. The bottles (54) were incubated for zero, one and three months in a dark room, exposed to light, watered daily thereafter for twelve days for fruiting bodies to spring out and harvested. P. ostreatus had best agronomic performance and P. tuber-regium removed hydrocarbons and heavy metals more than either P. ostreatus or P. pulmonarius under similar experimental conditions. The yield and mycoremedial performance of the three tested white-rot fungi demonstrated potentials for cleaning-up petroleum hydrocarbon contaminated soil, but their performance reduced from 5.0% (w/v) crude oil substrate contamination.