The Chernobyl exclusion zone is off-limits to humans, but it doesn’t deter all forms of life from thriving there.
Since the explosion of the Unit Four reactor at the Chernobyl Nuclear Power Plant nearly 40 years ago, various life forms have moved in, adapted, and seem to be thriving, possibly due to the absence of humans.
For one organism, the lingering ionizing radiation within the reactor structures might be advantageous.
Scientists have discovered a peculiar black fungus, Cladosporium sphaerospermum, thriving on the walls of one of the most radioactive buildings on Earth. Some researchers believe its dark pigment, melanin, might enable it to harness ionizing radiation, similar to how plants use light for photosynthesis. This potential process is called radiosynthesis.
Watch our video below for a summary of this unusual fungus and its unique abilities:
The intriguing aspect of C. sphaerospermum is its ability to thrive in ionizing radiation, though the exact mechanism remains unclear. Radiosynthesis is a theoretical concept that is challenging to confirm.
The enigma began in the late 1990s when microbiologist Nelli Zhdanova from the Ukrainian National Academy of Sciences conducted a survey in the Chernobyl Exclusion Zone to explore life forms in the vicinity of the devastated reactor.
During the survey, they discovered a diverse community of fungi, documenting an incredible 37 species, many of which were dark in color and rich in melanin.
C. sphaerospermum was the most prevalent among the samples, showing high levels of radioactive contamination.
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The finding was surprising, but subsequent research added to the intrigue.
Radiopharmacologist Ekaterina Dadachova and immunologist Arturo Casadevall, affiliated with the Albert Einstein College of Medicine in the US, led a team of researchers who discovered that exposing C. sphaerospermum to ionizing radiation did not harm it as it would with other organisms.
Ionizing radiation involves particles with enough energy to remove electrons from atoms, making them ionic. This process can break molecules, disrupt biochemical reactions, and even damage DNA, posing significant harm to humans but can be used to target cancer cells, which are particularly susceptible to its effects.
Interestingly, C. sphaerospermum appeared resistant and even grew more robustly when exposed to ionizing radiation. Experiments indicated that ionizing radiation altered the behavior of the fungal melanin, prompting further investigation.
The follow-up research by Dadachova and Casadevall in 2008 suggested a biological pathway akin to photosynthesis.
The fungus and similar organisms seemed to utilize ionizing radiation for energy conversion, with melanin functioning similarly to chlorophyll, which absorbs light.
Additionally, melanin acted as a protective barrier against the more detrimental effects of radiation.
These findings were echoed in a 2022 study, where researchers described the results of sending C. sphaerospermum to space and attaching it to the outside of the ISS, exposing it to cosmic radiation.
Sensors beneath the petri dish revealed that less radiation passed through the fungi compared to an agar-only control.
While the aim of this study was not to confirm radiosynthesis, it explored the fungus’s potential as a radiation shield for space missions, which is an intriguing concept.
However, as of that study, the exact function of the fungus remains unknown.
Researchers have yet to demonstrate carbon fixation reliant on ionizing radiation, metabolic benefits from ionizing radiation, or a specific energy-harvesting pathway.
“Actual radiosynthesis, however, remains to be shown, let alone the reduction of carbon compounds into forms with higher energy content or fixation of inorganic carbon driven by ionizing radiation,” wrote a team led by engineer Nils Averesch from Stanford University.
Radiosynthesis is a fascinating concept reminiscent of science fiction, but it is perhaps even more remarkable that this unique fungus is employing an unknown mechanism to neutralize a threat so hazardous to humans.
It is not alone. A black yeast, Wangiella dermatitidis, shows enhanced growth under ionizing radiation. Another fungus, Cladosporium cladosporioides, boosts melanin production but not growth under gamma or UV radiation.
This indicates that the behavior seen in C. sphaerospermum is not typical for all melanized fungi.
Related: Worms at Chernobyl Appear Mysteriously Unscathed by Radiation
Could this suggest an adaptation enabling the fungus to utilize intense light lethal to other organisms, or is it a stress response that aids survival under challenging conditions?
Currently, the answer remains elusive.
What is clear is that this unassuming, velvety black fungus is ingeniously using ionizing radiation to survive and possibly thrive in a place too dangerous for humans; life does, indeed, find a way.
Editor’s note: This article uses the spelling “Chernobyl” to reflect the historical context of the 1986 disaster, when Ukraine was part of the Soviet Union and Russian transliterations were widely used. The Ukrainian spelling is “Chornobyl”.
This article was fact-checked by Jess Cockerill and edited by Mike McRae. While we pride ourselves on our process, we are only human. If you spot a mistake, please let us know.
