Evaluation of Proximate Compositions, Morphology, and Trace Metal Profile of the Lung Oyster Mushroom Pleurotus pulmonarius (Agaricomycetes) Cultivated on Engine Oil-Polluted Soil Covered with Andropogon gayanus Grass Straw in Nigeria

Abstract

The growth, proximate composition, and trace metal profile of Pleurotus pulmonarius cultivated on oil-polluted soil covered with Andropogon gayanus grass straw were evaluated. The soil, polluted with 200 g/ wv condemned engine oil (8% pollution), was covered with 5 and 10 cm of grass straw, and the P. pulmonarius spawn inoculated. The mushroom growth was monitored over 21 days, measuring cap size, stipe length, stipe girth, and fresh weight for two harvests. Cap sizes ranged from 4.94 to 7.10 cm and 4.5 to 7.36 cm; stipe lengths, from 2.3 to 5.86 cm and 1.07 to 6.22 cm; stipe girths, from 3.04 to 3.93 cm and 1.77 to 5.08 cm; fresh weights, from 31.69 to 65 g/kg and 40.33 to 55 g/kg. At P ≤ 0.05, there was no significant difference in the growth parameters measured, nor was there any effect of crude oil pollution on the growth of the mushrooms. The mushroom fruiting bodies were also screened for possible presence of trace metals such as Fe (23.29-37.95 mg/kg); Zn (14.12-21.80 mg/kg); Pb (0.03-0.06 mg/kg); Cd (0.02 -0.032 mg/kg); Cr (0-0.05 mg/kg); and As (0-0.03 mg/kg). Comparing the trace metals, especially Pb, Cd, and Cr, which are detrimental to human health, with the provisional tolerable weekly intake (PTWI) that a consumer may take, it was shown that all the trace metals were within the provisional tolerable limit intake.