Elemental bioaccumulation and nutritional value of five species of wild growing mushrooms from South Africa.

The collection of wild edible mushrooms for use is an ancient practice. In this study, the elemental concentrations in five mushrooms were compared as a function of species and geographical location. The accumulation of metals from the substrate was found to be species dependent. Mushrooms excluded As, Be, Ca, Cd, Co, Cr, Fe, Mn, Ni and Si, and accumulated elements in the following order: Amanita pantherina (K > Na > Zn > Cu > Mg); Boletus edulis (edible) (K > Cu > Zn > Se > Na > Mg); Boletus mirabilis (edible) (K > Cu > Zn > Na > Mg); Lactarius deliciosus (edible) (K > Zn > Mg); and Russula sardonia (K > Na > Zn > Cu > Mg). Statistical analysis showed soil parameters to affect elemental accumulation by edible mushrooms more than inedible ones, especially for uptake of Se by B. edulis, which was antagonistic with As and Pb in the soil. The results also showed the edible mushrooms to contain proteins (25 - 55%), carbohydrates (34 - 69%), ash (3-6.5%) and lipids (0.8-5.3%).

Elemental distribution including toxic elements in edible and inedible wild growing mushrooms from South Africa.

Macro-elements (Ca, Fe, K, Mg and Na) and trace elements including some toxic (As, Be, Cd, Co, Cu, Mn, Ni, Pb, Se and Zn) were determined in edible and inedible wild-growing mushrooms (Amanita rubescens, Auricularia polytricha, Boletus edulis, Boletus mirabilis, Clavulina cristata, Helvella crispa, Lactarius deliciosus, Suillus luteus, Termitomyces microcarpus, Termitomyces reticulatus, Termitomyces clypeatus, Termitomyces umkowaanii, Amanita foetidissima, Amanita muscaria, Amanita pantherina, Aseroe rubra, Chlorophyllum molybdites, Ganoderma lucidum, Gymnopilus junonius, Hypholoma fasciculare, Lentinus villosus, Lepista caffrorum, Pycnoporus sanguineus, Panaeolus papilionaceus, Pisolithus tinctorius, Pleurotus ostreatus, Podaxis pistillaris, Russula sardonia, Scleroderma citrinum, Scleroderma michiganense). Analyses of samples were carried out using inductively coupled plasma-optical emission spectrometry. The elemental content in both edible and inedible mushrooms, in decreasing order, was found to be K >> Na > Ca > Mg > Fe > Mn > Zn > Cu > Se > Co > Ni > Be > Pb ≥ Cd > As. Our study revealed that the accumulation of metals from the soil is independent of whether mushrooms are edible or inedible as uptake is dependent on the soil quality and its environment. Edible mushroom species studied were found to be rich in Se (145-836% towards the RDA) with B. edulis being rich in it, C. cristata in Cu, S. luteus in Fe and H. crispa in Zn, and all contained low concentrations of toxic metals making them suitable for human consumption.