Lifestyle Influence on the Content of Copper, Zinc and Rubidium in Wild Mushrooms

The concentration of 18 trace elements in several species of fungi (arranged in three groups: ectomycorrhizae, saprobes, and epiphytes) has been determined. The measurements were made using the methodology of X-ray fluorescence. Higher contents of Cu and Rb (with statistical support) have been found in the ectomycorrhizal species. The Zn content reached higher concentrations in the saprophytic species. According to the normality test and the search for outliers, the species Clitocybe maxima and Suillus bellini accumulate large amounts of Cu and Rb, respectively, so that both can be named as “outliers.” The leftwards displacement of the density curves and their nonnormality are attributed to the presence of these two species, which exhibit hyperaccumulation skills for Cu and Rb, respectively. Regarding Zn absorption, no particular species were classified as outlier; therefore it can be assumed that the observed differences between the different groups of fungi are due to differences in their nutritional physiology. 1. Introduction Fungi are vital to ecosystem health as they play crucial roles in the geochemical cycles, element mobilization, and organic matter decomposition. As mycorrhizas they can improve plant growth by increasing uptake of nutrients, and as saprobes they are related to the recycling of biomass mineral constituents [1, 2]. Special mention deserves their role as wood decay agents since very little species of other groups of organisms are capable to attack recalcitrant substances such as cellulose or lignin. Because of the vital importance of fungi to the well-being of an entire ecosystem, the interaction of fungi with the organic and inorganic substrate should be traced. Over the last few years many articles have been published on the subject of elemental content in sporocarps of wild fungi. Some of them were focused on the perspective of the nutritional skills, or toxicity, when consumed by humans [3–10] and others tried to settle differences between different species or places [11, 12]. There are also some recent papers on the subject of the weathering properties of wild mushrooms and their relation with the mineral particles of the soil [13–18]. Some studies have shown a correlation between fungal metal concentrations and point sources of metal pollution such as smelters or roadsides [19, 20]. The sporocarps of basidiomycetes have a collection of morphological features, by which we can identify and discriminate the species, and also a short lifetime, generally no more than 7-8 days, although the mycelium may live for many years. Thus,