In 1986, the 4th unit of Chernobyl Nuclear Power Plant in Ukraine (erstwhile Soviet Union) suffered massive fire and steam explosion. The unprecedented accident released over 5% of the radioactive reactor core comprising of over 100 radioactive elements (mainly iodine-131, caesium-137, and strontium-90) in the environment. The radiation level was extremely high for the life forms in the vicinity to survive. The pine trees in 10 sq km area surrounding the accident site were killed within weeks due to exposure to lethal doses of radiation. However, certain molds and black fungi not only survived the dangerously high radiation level but were found to be thriving at the accident site. Subsequent studies isolated about 2000 strains of 200 species of fungi from the site. It was found that the fungal hyphae grew towards the source of ionizing beta and gamma radiation just the way green plants grow towards sunlight. More interestingly, exposure to ionising radiation seemed to have enabled the melanized fungal cells an enhanced growth indicating energy capture by melanin pigment in the presence of high energy radiation (similar to energy capture by chlorophyll in sunlight in photosynthesis). In 2022, an experiment aboard International Space Station (ISS) demonstrated that these fungi displayed the capabilities of radio-resistance and radio-synthesis in space as well. This suggests that the melanised fungi that survive and thrive in extreme radiation conditions like Chernobyl accident site can be used to shield deep-space human habitation from cosmic rays and to capture energy (from the cosmic rays) to enhance the energy-autonomy of the deep-space missions like Artemis towards future human habitations on the Moon and Mars.
Nuclear reactors worldwide mostly use enriched uranium containing about 3-5% Uranium-235 as fissile material (some advanced breeder reactors may also use Plutonium-239 or Thorium-233). The primary products of controlled fission of Uranium-235 in the reactors are lighter nuclei of Krypton and Barium, free neutrons and a large amount of energy. Further radioactive decays of unstable lighter fissile fragments (Krypton and Barium nuclei) release beta particles, gamma rays and other stable byproducts.
Chernobyl accident (1986)
In 1986, fire and steam explosion at the 4th unit of Chernobyl Nuclear Power Plant in Ukraine (then Soviet Union) resulted in release of over 5% of the radioactive reactor core into the environment. The unprecedented accident released over 100 radioactive elements in the environment, the main were iodine-131, caesium-137, and strontium-90. The latter two (viz. caesium-137 and strontium-90) are still present in significant amount in the local environment since they have longer half-lives of around 30 years. These two isotopes are primarily responsible for the Exclusion Zone being the most radioactively contaminated area on Earth.
Some places in the Exclusion Zone near the site have an extremely high radiation levels. The destroyed reactor building has radiation level of over 20,000 roentgens per hour (for a comparison,around 500 roentgens over five hours is the lethal dose of radiation, which is less than 1% of the radiation near the destroyed reactor site).
The radiation level in the 10 sq km area surrounding the Chernobyl Plant within the Exclusion Zone (called Red Forest) was so high that thousands of pine trees died within weeks after being exposed to approx. 60-100 Grays (Gy) of radiation. This radiation dose was lethal to pine trees in the area which turned rusty-red and died. Even today, the gamma rays peak at around 17 millirem/hour (about 170 µSv/h) at some places in the Red Forest. Gamma rays are very high energy radiation. They penetrate deep and knock off electrons from atoms and molecules and form ions and free radicals that cause irreparable damages to cells and tissues including vital biomolecules like DNA and enzymes. Exposure to very high doses of gamma rays results in death of living organisms as what happened to the pine trees around the Chernobyl accident site. But not always!
Certain fungi not only survived but thrived in high-radiation Chernobyl accident site
While pine trees in 10 sq km area surrounding the accident site were killed within weeks due to exposure to extremely high radiation level, certain black fungi, particularly Cladosporium sphaerospermum and Alternaria alternata were observed to be growing in the vicinity of the damaged 4th unit few years after the accident even though the radiation level was/is still lethal. This was a surprise. By 2004, various studies isolated about 2000 strains of 200 species of fungi from the accident site.
Interestingly, it was found that the fungal hyphae grew towards the source of ionizing radiation (just the way plants grow towards sunlight showing phototropism). Upon measurement of fungal response to ionizing radiation, researchers showed that both beta and gamma radiation promote directional growth of hyphae towards the source.
| Key properties of Chernobyl fungi |
| Radio-resistance – ability of certain fungi to survive high radiation level |
| Radiotropism – tendency to grow or move towards a source of ionizing radiation. – analogous to phototropism where plants grow in response to light |
| Radiosynthesis – melanised Chernobyl fungi convert high energy ionising radiation into chemical energy using melanin pigment. – analogous to photosynthesis |
| Radiotrophy – process of using ionising radiation as an energy source |
Because melanized microbial species are more common in nature, it was thought that melanin pigment has a role in this remarkable ability of some fungi to survive and thrive in the soils contaminated with fissile fragments (radionuclides). An experiment published in 2007 found that this indeed was the case. Exposure of melanin to ionizing radiation is the key. The ionizing radiation changed electronic properties of melanin pigments enabling melanized fungal cells an enhanced growth following exposure to ionizing radiation. This indicated melanin has a role in energy capture (radiosynthesis), similar to what chlorophyll has in photosynthesis. This also meant possibility of using these fungi in cleanup of radionuclides contamination.
Deep-space Human missions and habitations
In the long run, all planetary civilization run existential threats from impacts from space hence the imperative for humans to become a multi planet species. Deep space human missions are envisioned for setting up human habitations beyond the earth. Artemis Moon Mission is a beginning in this direction which aims to create long term human presence on and around the Moon in preparation for human missions and habitations on Mars.
One of the biggest challenges before the deep-space human missions is posed by the constant flux of powerful cosmic rays that pervade everywhere in space. Earth’s magnetic field protects us from cosmic rays on earth, but it is biggest health risk for human missions in space. Therefore, deep-space missions require protective shields from cosmic rays. On the other hand, cosmic radiation could also be an unlimited source of energy and enhance energy-autonomy of the longer deep-space missions if there were suitable technology to harness them.
Fungi thriving in high-radiation Chernobyl site may offer a solution to challenges posed by cosmic radiation to deep-space human missions and habitations
As discussed above, certain melanised fungi are found to grow in the high-radiation contamination site of the damaged Chernobyl Nuclear Power Plant and other high-radiation environments on Earth. Apparently, the melanin pigments in these fungi utilise the high-energy radiation to generate chemical energy (just the way the chlorophyl in the green plants use sun’s rays in photosynthesis). Thus, the Chernobyl fungi may have potential to act both as protective shield against high-energy cosmic rays (radio-resistance) as well as energy producer (radiosynthesis) in deep-space missions if their capabilities extend to cosmic rays in space. Researchers tested this in space.
The fungus Cladosporium sphaerospermum was cultivated aboard the International Space Station (ISS) to study its growth and ability to absorb and dampen ionizing cosmic rays over 26 days in a condition mimicking habitation on the surface of Mars. The result showed cosmic radiation attenuation due to fungal biomass and a growth advantage in space suggesting that the capabilities displayed by certain fungi at Chernobyl accident site is extendable to cosmic rays in space.
This is too early to say but it may be possible in future to transport these fungi to the Monn and Mars where with the help of suitable infrastructure these fungi would become functional as chemical energy producer.
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References:
- Zhdanova NN, et al 2004. Ionizing radiation attracts soil fungi. Mycol Res. 108: 1089–1096. DOI: https://doi.org/10.1017/S0953756204000966
- Dadachova E., et al 2007. Ionizing Radiation Changes the Electronic Properties of Melanin and Enhances the Growth of Melanized Fungi. PLOS One. DOI: https://doi.org/10.1371/journal.pone.0000457
- Dighton J., Tugay T., and Zhdanova N., 2008. Fungi and ionizing radiation from radionuclides. FEMS Microbiology Letters, Volume 281, Issue 2, April 2008, Pages 109–120. DOI: https://doi.org/10.1111/j.1574-6968.2008.01076.x
- Ekaterina D. & Casadevall A., 2008. Ionizing radiation: how fungi cope, adapt, and exploit with the help of melanin. Current Opinion in Microbiology. Volume 11, Issue 6, December 2008, Pages 525-531. DOI: https://doi.org/10.1016/j.mib.2008.09.013
- Averesch N.J.H. et al 2022. Cultivation of the Dematiaceous Fungus Cladosporium sphaerospermum Aboard the International Space Station and Effects of Ionizing Radiation. Front. Microbiol., 05 July 2022. Sec. Extreme Microbiology Volume 13 2022. DOI: https://doi.org/10.3389/fmicb.2022.877625
- Sihver L., 2022. Chernobyl Fungi as an Energy Producer. Available at https://ui.adsabs.harvard.edu/abs/2022cosp…44.2639S/abstract
- Tibolla M.H., and Fischer J., 2025. Radiotrophic fungi and their use as bioremediation agents of areas affected by radiation and as protective agents. Research, Society and Development. DOI: https://doi.org/10.33448/rsd-v14i1.47965
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 suffered massive fire and steam explosion. The unprecedented accident released over 5% of the radioactive reactor core comprising of over 100 radioactive elements (mainly iodine-131, caesium-137, and strontium-90) in the environment. The radiation level was extremely high for the life forms in the vicinity to survive. The pine trees in 10 sq km area surrounding the accident site were killed within weeks due to exposure to lethal doses of radiation. However, certain molds and black fungi not only survived the dangerously high radiation level but were found to be thriving at the accident site. Subsequent studies isolated about 2000 strains of 200 species of fungi from the site. It was found that the fungal hyphae grew towards the source of ionizing beta and gamma radiation just the way green plants grow towards sunlight. More interestingly, exposure to ionising radiation seemed to have enabled the melanized fungal cells an enhanced growth indicating energy capture by melanin pigment in the presence of high energy radiation (similar to energy capture by chlorophyll in sunlight in photosynthesis). In 2022, an experiment aboard International Space Station (ISS) demonstrated that these fungi displayed the capabilities of radio-resistance and radio-synthesis in space as well. This suggests that the melanised fungi that survive and thrive in extreme radiation conditions like Chernobyl accident site can be used to shield deep-space human habitation from cosmic rays and to capture energy (from the cosmic rays) to enhance the energy-autonomy of the deep-space missions like Artemis towards future human habitation on the Moon and Mars.){kind=link}