Bioaccumulation potential of Pleurotus florida on Engine oil polluted soil using different substrates

Abstract

The accumulation of environmental pollutants in edible mushrooms has raised concerns regarding food safety and environmental sustainability. This study investigated the bioaccumulation of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in Pleurotus florida cultivated on different agricultural substrates grown on engine oil-polluted soil. The experiment was conducted in the laboratory of the Department of Public Health and Preventive Medicine, College of Veterinary Medicine, Michael Okpara University of Agriculture, Umudike, Abia State, Nigeria. Four substrates sawdust, sugarcane bagasse, rice straw, and Andropogon straw—were used for mushroom cultivation. The experimental design Completely Randomized Design (CRD) with four treatments replicated five times. Polluted soil collected from a mechanic workshop was incorporated at different levels (50 g, 100 g, 150 g, and 200 g) into 200 g of each pasteurized substrate and inoculated with spawn of Pleurotus florida. Growth parameters such as fresh weight, dry weight, no of fruiting bodies, stipe length, and cap diameter were recorded. Samples of the polluted soil and harvested mushrooms were analyzed to determine the concentrations of heavy metals and PAHs. The results revealed the presence of five heavy metals zinc (Zn), chromium (Cr), arsenic (As), cadmium (Cd), and copper (Cu) in the engine oil-polluted soil before cultivation. Significant (P ≤ 0.05) accumulation of Zn, Cr, As, and Cd was detected in the mushroom fruiting bodies harvested from Andropogon straw, sugarcane bagasse, rice straw, and the control treatment. However, there was no significant difference in copper accumulation across the substrates and control. Analysis of PAHs showed detectable accumulation in mushrooms grown on most substrates, with the highest concentration of phenanthrene recorded in mushrooms cultivated on sugarcane bagasse (1.91 ± 0.00) and the lowest concentration of fluorene observed in mushrooms grown on sawdust (0.17 ± 0.00). No PAH accumulation was detected in the control treatment. The findings demonstrate that Pleurotus florida can accumulate heavy metals and PAHs from contaminated substrates, highlighting its potential for environmental remediation. However, the study also emphasizes the importance of substrate selection in mushroom cultivation to reduce the risk of contaminant accumulation in edible fruiting bodies. Among the substrates tested, sawdust proved to be the most suitable and safer substrate for commercial mushroom production.