Bioremediation of spent diesel oil contaminated-soil by Pleurotus ostreatus (Jacq. Fr) P. Kumm

Abstract

Soil contamination with petroleum products has gained much attention globally in the last decade owing to their toxic
effects on the ecosystem. Remediation of such contaminated-soil before crop cultivation becomes imperative. In this
study, the potential of Pleurotus ostreatus to biodegrade spent diesel oil contaminated-soil for a period of two months
was investigated. Four kilogram of top soil was contaminated with varying compositions (5, 10 and 15% w/v) of spent
diesel oil was inoculated with 50 g of P. ostreatus, incubated at 28 ? 2oC in triplicates and analyzed for some physico-
chemical parameters before and after incubation. The overall effect of the fungus on spent diesel oil contaminated-soil and
straw levels showed that the highest nutrient content was at 15% contamination level with 10.8%, 17.59%, 1.12%, 1.14
cmol/kg, 8.88 cmol/kg and 1.78 cmol/kg respectively for organic carbon, organic matter, total nitrogen, potassium, calcium
and magnesium contents except for phosphorus with the highest value of 18.12 mg/kg observed at 5% contamination
level. Also, 15% spent diesel oil contaminated-soil had the highest overall heavy metal reduction with 8.45, 7.43, 5.79,
42.81, 5.78 and 3.18 mg/kg respectively for Cd, Cr, Ni, Pb, Cu and Zn. At each incubation period, the pH of each contaminated-
soil ranged from 7 to 8. This improvement of soil nutrient content as well as reduction in the heavy metal contents of the
soil could be an indication of degradation of organic and inorganic contaminants by P. ostreatus.