Heavy metals accumulation in the oyster mushroom basidiomes cultivated on different substrates

Abstract

The aim of this study was to assess the ability of oyster mushrooms (<i>Pleurotus ostreatus</i> (Jacq.) P. Kumm.) to absorb heavy metals (Fe, Zn, Cu, Co, Mn, Ni, Cr, Cd, and Pb) from different plant-based substrates and to determine the bioaccumulation factor of the aforementioned heavy metals from the substrate to the oyster mushroom basidiomes. The substrate used in this study were: maize straw, beech sawdust supplemented with wheat bran at a rate of 20%, a mixture of maize straw and spent coffee grounds in a ratio of 70:30, and a mixture of maize straw and spent coffee grounds in a ratio of 50:50. Heavy metal contents in substrate and mushroom samples were analyzed by atomic absorption spectroscopy using the Shimadzu AA-7000 device, while the bioaccumulation factors of oyster mushroom for each investigated heavy metal were calculated from the heavy metal content in mushrooms divided by that found in substrates. The study showed that oyster mushrooms have a high capacity to absorb Zn and Cd from the growing medium and bioaccumulation factor values for Zn and Cd determined in this study strongly support this observation. On the other hand, bioaccumulation factor values for Ni, Fe, and Mn were less than 0.3 and ranged from 0.04 to 0.05, from 0.09 to 0.12, and from 0.10 to 0.25, respectively. In general, the results of this study lead to the conclusion that substrate chemical composition strongly affects the heavy metal accumulation in oyster mushroom basidiomes. The results of this study also showed that oyster mushrooms can be considered a promising species for Cd and Zn bioremediation.