Potential Use of Mushrooms and Spent Substrate in decontamination of Oil Contaminated Soil

Abstract

Preliminary studies on the enhancement of biodegradation of used lubricating oil, a petroleum bye product, in soil amended with dried powdered Pleurotus tuberregium (PT) and Pleurotus ostreatus fruits (PO), Powdered sclerotium of pleurotus tuberregium (SCPT) and spent substrate of Pleurotus ostreatus (SPO) was carried out in randomized pots of 400g of soil. The objective was to study the effect of mushroom and spent substrate as a biocatalysts in the clean up of soil contaminated with petroleum products in the tropics. An absorption spectrophotometer with a wavelength of 640nm was used to analyse the oil content of the contaminated soil after extraction with n-hexane. After seven weeks, the amount of lubricating oil in the untreated soil (not amended with the mushroom fruits, sclerotium and spent substrate) dropped from 960mg/g to 282mg/g. On application of varying quantities up to 60g each of PT, PO, SCPT, SPO, into the lubricating oil contaminated soil and left for seven weeks, the residual lube oil concentration dropped drastically from 960mg/g to 0.05mg/g, 0.5mg/g, 1mg/g and 2.7mg/g respectively. PT supported faster break down of the oil than PO, SCPT and SPO. Corrobaration between higher crude protein and higher biodegradation efficiency was noted. The PH of untreated soil slowly dropped from 8.15 to 7.77 in the 7th week while PH of oil contaminated soil was 7.0 for the same period with increased microbial diversity and population. Results suggest that mushroom and spent substrate could be employed as cheap clean up agents of oil contaminated soil in the tropics.