For their part, thorium and uranium accumulated mostly in Hypholoma fasciculare, with concentrations of 3.63 and 4.13 g/g, respectively, "despite being a species that lives on fallen tree trunks and is isolated from the mineral substances of the soil".
The scientists found no significant differences in the metal levels when comparing mushrooms collected from different substrates, habitats and localisations. The only exception was with thorium, which accumulates more in mushrooms which grow on wood (such as Hypholoma fasciculare or Gymnopilus spectabilis) than in those which have contact with the organic material of the soil (Tricoloma ustaloides and Pisolithus arrhizus).
New lines of research
To confirm that the type of substrate can take on a more important role than reflected in the study, the researchers have embarked on a new project in which they will analyse the presence of 19 chemical elements (toxic and non-toxic) in 15 species of edible mushroom.
"The real issue is that those mushrooms that form ectomycorrhizae are specially adapted to absorb chemical elements from the mineral particles of the soil, and give them to the plant. This is their contribution to symbiosis, and, the more effective they are in providing nutritional elements to the plant, the closer their connection to it, and the more sugars from photosynthesis they can access, which is what they are ultimately looking for", explains Juan Antonio Campos.
This type of mushroom carries out an indiscriminate acid attack on the mineral particles of the soil and absorbs elements in quantities relative to the mineralogical composition of the soil. "In some contaminated soils, or those with particular mineralogical characteristics, the mushrooms collected can reach such high concentrations of toxic element
FECYT - Spanish Foundation for Science and Technology