The risk of high mercury accumulation in edible mushrooms cultivated on contaminated substrates

Mercury (Hg) exposures represent a significant worldwide health issue. At the same time its content in cultivated mushrooms is not effectively regulated. The present study investigated how substrate contamination with Hg (0.1-0.5 mM) affects its accumulation in stipes and caps of Agaricus bisporus E58, Pleurotus ostreatus H195 and Hericium erinaceus HE01, mushroom growth and composition of macronutrients. The greatest Hg accumulation was demonstrated for caps. Generally, Hg uptake increased in a concentration-dependent manner and exceeded 44 mg kg−1 (P. ostreatus), 116 mg kg−1 (A. bisporus) and 53 mg kg−1 (H. ercinaceus) in caps after 0.5 mM was added to the substrate. Importantly, an increase in Hg accumulation was also significant and potentially hazardous for human health at the lowest assayed concentration. A. bisporus and P. ostreatus revealed high resistance to Hg and declined its biomass only at 0.4 and 0.5 mM concentration. The presence of Hg did not alter the macronutrient composition (total carbohydrates, proteins and fats). These results highlight the significant role of proper substrate selection in mushroom cultivation to avoid exposing consumers to harmful Hg levels and further health consequences.