Can a “radiation-eating fungus” solve all our radioactive waste problems?
Chernobyl’s black fungus and frogs captivate scientists and fascinate the internet community. Numerous myths have grown up around the “Chernobyl fungus” –aided by false information and AI-generated images. But what is really behind the phenomenon?
“The fungus that converts radiation into life”, “Radiation-gobbling fungus” or the “Chernobyl fungus”: the headlines are gripping and speculations abound. At the centre of this commotion is a black mould with special properties.
Could this fungus solve our radioactive waste problem if we simply let it eat the waste? As is so often the case, when something appears too good to be true, it is.
While the fungus does indeed exist, its abilities have been exaggerated or simply misrepresented. It does not help that its appearance is (too) often generated by artificial intelligence.
What is so special about this fungus?
The fungus is far less spectacular, but much more complicated than many social media posts would have us believe. Let us start with the name: the fungus has the tongue-twisting name Cladosporium sphaerospermum.
This black mould has been known since 1886. The Chernobyl nuclear disaster occurred exactly 100 years later. In the 1990s, the fungus was detected in the Chernobyl Exclusion Zone thought to be uninhabitable by any form of life – it was even found living on what was left of the reactor walls.
Nelli Zhdanova, a Ukrainian microbiologist, was so fascinated by this discovery that she collected samples and began researching – and uncovered astonishing results: the black mould cannot only resist radiation – like plants reaching for sunlight, it is actually attracted to the radiation sources.
The mysterious pigment
The fungus converts gamma radiation, a form of ionising energy, into energy. Gamma radiation arises from the decay of radioactive substances.
The fungus has a special metabolism that allows it to feed on the radiation’s energy, a process called radiosynthesis. The name is derived from photosynthesis, the process by which plants transform light into energy.
The energy transducer responsible for this radiosynthetic metabolism is a common pigment: melanin, also found in humans, where it determines skin and hair colouring. The cell walls of the black mould are packed with this pigment. Nelli Zhdanova assumed that, just as darker skin protects more effectively from ultraviolet radiation, the melanin in the fungi acts as a shield against ionising radiation.
This theory was further compounded by the observation that tree frogs, which are normally green, are much darker in colour, even black, around the damaged Chernobyl power plant. They have more melanin in their cells than their green counterparts and are more resistant and more fertile. The tree frog population in Chernobyl is therefore turning from green to black.
Despite numerous scientific endeavours to unravel the mystery of melanin, much remains unknown. Exactly how melanin triggers radiosynthesis is still being researched.
However, the fact that ionising radiation drives and can even accelerate the metabolism of the mould is certain.
This is why the mould and many of its related species feel particularly at home in the dystopian Chernobyl environment.
What the fungus cannot do
The fascinating findings raised hopes that the fungus could be put to special use. Would it not be wonderful, for example, if mould could rid contaminated sites of radiation by simply eating it up?
The sad truth is that it cannot. While mould does thrive due to the radiation, it only absorbs radiation on a very small scale. What is more, the radiation source remains: toxic radionuclides are neither removed from the environment nor rendered harmless by the metabolism of the fungus. To say that the fungus eliminates – let alone devours – radioactivity is simply wrong.
Equally incorrect are the many images and videos of this remarkable master of survival. Much of the related content is AI-generated. The dystopian-looking images are adapted to the fast-paced world of social media and are probably one reason why the fungus is still in the spotlight years after its discovery – in addition to its unquestionably impressive properties.
No reason for disappointment
The misleading representations are lamentable, but this does not mean that the fungus is uninteresting. It could be put to good use elsewhere.
The fungus is a welcome guest in the field of space research. It has even been flown into outer space for experiments, where it was exposed to cosmic radiation – and grew faster than on Earth. However, it is not yet possible to say whether this is only due to cosmic radiation or perhaps also to the effects of weightlessness. In all likelihood, it is a combination of the two factors.
Protective shield in outer space
The inhospitable conditions in outer space push humans and technology alike to their limits. Cosmic radiation, originating from the sun, (exploded) stars and black holes, constantly spreads through the universe.
On Earth, the atmosphere protects us from cosmic radiation. However, spaceships and space stations potentially constructed on the moon or Mars must be able to contain cosmic radiation. Research is being carried out into whether the mould could serve as a natural protective layer.
Despite – or perhaps because of – the many unanswered questions, scientific interest in black mould and melanin remains undiminished. Even if radiation-devouring fungi and frogs continue to be nothing but a pipe dream, these fascinating creatures have once again impressively demonstrated how remarkably adaptive nature is.
Images:
Header: Science Pulse / Wikimedia Commons by Medmyco / Montage: Nagra
Frogs: «Ionizing radiation and melanism in Chornobyl tree frogs» by Pablo Burraco & Germán Orizaola
Spacewalk on the ISS: Wikimedia Commons by NASA
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