Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

Radionuclides occur naturally and can be released into nature through anthropogenic effects. Through leaching and migration, also the anthropogenically released radionuclides can enter the groundwater and endanger the environment, animals and humans. However, the microbial community living in the soil may influence the mobility and thus the migration behaviour of radionuclides.
Since the Chernobyl accident at the latest, it became clear that various fungi are able to accumulate considerable amounts of heavy metals and radionuclides in their fruiting bodies [1-3]. However, it has not yet been determined, which processes lead to this significant accumulation in the fungal fruiting body.
For this reason, the interaction of a model fungus, namely Schizophyllum commune, with various radionuclides was studied in detail in the steps of binding and uptake by the fungal cells and transport within the mycelium.
For the visualization of the radionuclide and heavy metal transport through the hyphae, TEM and STEM imaging in combination with Energy-dispersive X-ray spectroscopy analysis were used to locate accumulation sites within the cells and to identify the formed species. The first results with uranium show that it is accumulated in form of phosphate minerals mainly on the cell membrane. Furthermore, microcosm experiments were conducted in which the bidirectional growth of the fungus was exploited: parts of the mycelium were growing upwards, while the other parts were growing into the contaminated soil. In order to check the transport of soil contaminants through the hyphae, the part of the mycelium that has no direct contact with the soil was sampled and analysed by ICP-MS. First results show that uranium could be detected in the samples, suggesting transport through the hyphae.
In addition to the transport of uranium, the experiments also investigate the transport of europium as an analogue for trivalent actinides, as well as the transport of inactive caesium and strontium within the mycelium.