The content of selected risk element in fruit bodies of mushrooms with medicinal benefits

This dissertation thesis is focused on determination of detrimental and essential elements in fruiting bodies of selected medicinal mushrooms. Auricularia auricula-judae, Tylopilus felleus, Pleurotus ostreatus, Flammulina velutipes, Armillaria ostoyae and Coprinus comatus were studied. Individual samples were collected from selected sites in South Bohemia. Pleurotus ostreatus was cultivated on the block of the substrate. Individual elements were determined using atomic absorption spectrometry with the flame or electrothermal atomization and flame photometry. Wild growing Auricularia auricula-judae was a good source of Ca and Mg (2200 a 2080 mg kg-1 dry matter) and Tylopilus felleus strongly accumulated Rb, Cd, Cu, Zn, Se and Mg (bioconcentration factors: 65.7; 2.47; 2.32; 1.93; 1.67 and 1.27). Another studied wild growing mushroom species was Flammulina velutipes; it was characterized with significant contents of Ca, Fe, Mg, Mn and Zn (375, 112, 1200, 26 and 98 mg kg-1 dry matter). For Armillaria ostoyae, high contents of the following elements were determined (mg kg-1 dry matter): Ag (5.6), Ca (149), Cu (29), Fe (186), Mg (1100), Mn (30) and Zn (40). The last wild growing species studied was Coprinus comatus. It strongly accumulated Ag, Cd, Cu, Se and Rb (bioconcentration factors: 12; 2.5; 2.3; 1.8 and 1.1). The concentrations of detrimental elements were generally rather low indicating no considerably negative effect on human health in the case of studied species consumed as a delicacy or used as food supplements. On the other hand, the mushroom species can be used as an alternative source of essential elements (especially Zn and Se). An experiment with enrichment of the cultivation substrate with zinc and selenium was performed in the case of Pleurotus ostreatus. The increase in the zinc content in fruiting bodies was low, thus it can be concluded that the level of enrichment indicates no considerable effect on the final content of zinc in fruiting bodies. The bioconcentration of selenium was totally different. The addition of 1 mg of Se (in the form of Na2SeO3) into the cultivation substrate (cca 2 kg) increased the content of Se in fruiting bodies to about 3 - 6 mg kg-1 dry matter. This content was one order higher compared to the Se content in fruiting bodies harvested from the substrate with no Se addition. In the case of the addition of 5 mg of Se, there was a further significant increase in the content of this element to about 40 - 60 mg kg-1 dry matter