Mushrooms from two metal-contaminated areas in Norway: occurrence of metals and metallothionein-like proteins

Abstract

This study tested the hypothesis that concentrations of metallothionein-like (MT-like) proteins in fruiting bodies of wild-growing macrofungi reflect exposure to the metals Cd, Cu and Zn. Screening for these proteins was done by taking 44 samples of seven species of macrofungi from two metal-polluted areas in Norway, namely Odda and Sulitjelma. Concentrations of Cd, Cu and Zn were measured in fruiting bodies and topsoil, the highest of which were observed in fruiting bodies – 126 μg g −1 for Cd, 427 μg g −1 for Cu and 396 μg g −1 for Zn. A large intra- and inter-specific heterogeneity in metal uptake was displayed between fruiting bodies from the same soils. Cd,Zn–MT-like proteins were detected in all samples, except one stipe of Boletus edulis , whereas only 72% of the samples contained detectable levels of Cu–MT-like proteins. However, concentrations of MT-like proteins did not reflect variations in metal concentrations. Low content of cysteine in Cd-binding protein fractions from Amanita muscaria collected in Odda indicates that no proteins of the metallothionein family were present in this species. Onthe contrary, these protein fractions share several characteristics with cadmium–mycophosphatins.