The importance of Cu × Pb interactions to Lentinula edodes yield, major/trace elements accumulation and antioxidants

Due to the use of various substrates in the production of edible mushrooms which may contain metals, including Cu and Pb, it is important to understand the influence of mutual interactions between them in the process of their accumulation in fruit bodies. For this reason, the effects of Cu, Pb, and Cu × Pb on yield, accumulation of five major elements (Ca, K, Mg, Na and P), trace elements (Cu, Pb and Fe) and some bioactive compounds in Lentinula edodes fruit bodies were studied. Both the metals were added in doses of 0.1 and 0.5 mM (Cu0.1, Cu0.5, Pb0.1, Pb0.5 and their combinations). The addition of the metals resulted in a reduction in size, amount and finally yield of fruit bodies. Depending on the presence of Cu and or Pb and their concentration in the substrate, both antagonism and synergism may occur. The influence on the accumulation of other determining elements was also recorded. Among phenolic compounds, phenolic acids and flavonoids were detected. 2,5-Dihydroxybenzoic acid dominated in fruit bodies in the control variant, Pb0.1, Pb0.5 and all experimental variants enriched with Cu + Pb, while gallic acid was the major phenolic after Cu0.1 and Cu0.5 addition. Only protocatechuic acid content increased in all combinations. A significant decrease of all aliphatic acid contents in comparison to the control variant was observed in the Cu0.1 and Pb0.1 variants. Significant stimulation of aliphatic acid synthesis was recorded in Cu0.5 and Pb0.5 variants and in the mixture of both the metals. The additions pointed to the possible role of the determined molecules in detoxification mechanisms.