As a result of the Chernobyl reactor catastrophe in 1986, many soils are still radioactive. But mushrooms could possibly serve as a cleaning command. Because researchers have now discovered that various types of fungi filter the elements europium, americium and curium out of the soil. The dangerous heavy metals then remain stored in the fungus until they have decayed, where they cannot cause any great harm to either humans or nature.
The mushrooms that end up in our cream sauce and omelets are only a fraction of the entire mushroom body. The rest of it, the so-called mycelium, lies underground and can extend over several hundred hectares. But the fine network of the mycelium has another superpower: it can absorb radioactive heavy metals, which then accumulate in the fungus. In earlier experiments, scientists have already been able to prove that the common fissure can take up large amounts of uranium in its cells without dying.
Fungus meets heavy metal
Researchers led by Alix Günther from the Helmholtz-Zentrum Dresden-Rossendorf have now investigated whether fungi can also store the rare earth metal europium. Although europium itself is not radioactive, it is representative of elements from the actinide group, including americium and curium. "Americium in particular will be responsible for high radiotoxicity in Chernobyl in the future," explains Günther. Although it was not released when the reactor exploded, plutonium was released, which decays into americium with a half-life of 14.4 years. The americium content will therefore continue to rise and will only reach its maximum value approximately 70 to 80 years after the accident, according to the scientists.
In order to investigate how the Americium representative europium interacts with different species of fungi, Günther and her team brought the element into contact with four wood and soil-dwelling fungi: the common split-leaf, the oyster-oyster mushroom, the tabby saw-belly and the pink-leaved chakra. Using microscopy and spectroscopy, the scientists were then able to observe how the fungi reacted to the europium.
Conceivable use as a floor cleaner
The result: the different fungi interact very differently with europium. Among other things, the researchers observed that the different types of fungi accumulate the heavy metal at different locations in the cell, for example on the cell surface, in the cell membranes or in some cases in the cytoplasm. For example, while the pink-leaved banewort binds only small amounts of europium and distributes it finely in the cell, the fissured phylloxera can bind up to four times more europium than other fungi, namely on the outside of the cell wall.
With the knowledge gained, methods could now be developed with which areas contaminated with heavy metals can be used for agriculture again. "Thanks to the old age of some types of fungi, some radioactive substances could be stored until they decay. For this reason, they could be suitable for rapid radiation protection on the one hand and for the remediation of contaminated soil on the other. And we also see the possibility of cleaning contaminated water,” says Günther. However, the scientists would first have to "understand the molecular processes and the transport within the organism more precisely," adds her colleague Johannes Raff.
Source: Helmholtz Center Dresden-Rossendorf, Article: Science of The Total Environment, doi: 10.1016/j.scitotenv.2022.158160