Elemental and Cu–Zn isotopic compositions of two bolete mushrooms grown on contrasting substrates

Abstract

We studied elemental and Cu–Zn isotopic compositions of Boletus edulis and Xerocomus chrysenteron mushroom samples collected from three small catchments underlain by contrasting bedrock (leucogranite, amphibolite, and serpentinite). Elements such as Ag, P, K, Zn, S, Cd, and Rb are significantly enriched in the mushroom's fruiting bodies relative to the substrate. All analyzed elements are distributed unevenly within the fruiting bodies, with the cap and sporophore generally containing higher amounts of trace elements. Overall, the studied samples of the B. edulis more efficiently accumulate nutrients and minerals than the X. chrysenteron samples. Concentration of most trace elements in mushrooms is not site-dependent with the exception of Ca, Rb, Ti, Ba and Sr. Isotopic composition of mushrooms is characterized by higher uptake of heavier isotopes of Zn (Δ66Znstipe-soil = 0.48–0.77‰) for the both species, lighter isotopes of Cu (Δ65Custipe-soil = −0.73 to −1.52‰) for B. edulis, and heavier Cu isotopes (Δ65Custipe-soil = +0.37 to +0.43‰) for X. chrysenteron. The B. edulis samples are characterized by (δ65Custipe > δ65Cucap > δ65Cusporophore) and (δ66Znstipe > δ66Zncap > δ66Znsporophore) within-mushroom isotope distribution schemes, whereas the X. chrysenteron samples display different Cu (δ65Custipe < δ65Cucap > δ65Cusporophore) and Zn (δ66Znstipe > δ66Zncap < δ66Znsporophore) isotope distribution schemes. Changes in fungal isotopic signatures relative to the substrate and within the fruiting body suggest that both fungi species fractionate Cu and Zn isotopes with significantly pronounced differences between the species.