Chernobyl fungi use nuclear energy for growth—can we do it too?

Nuclear reactions in the Sun are powerful sources of electromagnetic radiation.  The Sun emits infrared radiation, visible light, ultraviolet rays, and even more powerful X-rays and gamma rays.  Most of this radiation is filtered out by the atmosphere.  What passes through—visible light—drives photosynthesis.

Virtually no gamma radiation reaches the Earth’s surface from space. However, rocks containing uranium and thorium emit gamma rays. Although uranium and thorium decay produces little or no gamma radiation directly, certain shorter-lived elements in their decay chains—radioactive forms of lead, bismuth, actinium, and thallium—emit gamma rays. These radioactive elements are present in very small amounts compared to their uranium and thorium “parents.”

Have any organisms evolved to use gamma radiation as an energy source, much like green plants use visible radiation? The high energy of gamma radiation creates challenges for life. Gamma rays eject electrons from atoms and turn them into charged ions (hence the term, “ionizing radiation”). They break chemical bonds, inactivate proteins and chromosomal DNA, and disrupt cell membranes.

However, scientists have discovered fungi that have risen to these challenges and that flourish in an environment with high gamma radiation—Chernobyl.

Chernobyl fungi have large amounts of melanin, a complex molecule responsible for black hair.  Melanin acts as a protective radiation shield, interacting with gamma rays and scavenging the ions they create. But Chernobyl fungi appear to go further, using melanin to enable gamma rays to enhance the cellular processes that create usable energy.

In a 2008 paper, "Ionizing radiation: how fungi cope, adapt, and exploit with the help of melanin,” Ekaterina Dadachova and Arturo Casadevall reported that “melanized fungal cells manifested increased growth relative to non-melanized cells after exposure to ionizing radiation,” adding that this “raised the intriguing possibility that melanin can function in energy capture and utilization.”

They proposed that melanin has “functions analogous to other energy harvesting pigments such as chlorophylls.” Chlorophylls transfer excited electrons into the photosynthetic electron transport chains in green plants. Others picked up on this idea, coining the term “radiosynthesis” as an analogue to photosynthesis.

Little follow-up research has been done to test the theory of radiosynthesis, but it continues to intrigue the scientific community. It ha spawned recent articles with titles such as “Black Fungus that Eats Radiation for Breakfast,” The mysterious black fungus from Chernobyl that may eat radiation, and “Inside Chernobyl, a Fungus Has Been Quietly Feasting on Radiation.”

All nuclear reactions give off radiation, but in different forms. Gamma radiation is considered to be pure energy with no electrical charge; beta radiation is emitted as electrons (negatively charged particles with a small mass). 

In their 2008 study, Dadachova and Casadevall used rhenium-188 (¹⁸⁸Re) as a radiation source. A man-made medical isotope used in targeted cancer therapy, ¹⁸⁸Re emits both gamma and beta rays. Dadachova and Casadevall cite other studies showing that Chernobyl fungi are attracted to either gamma or beta radiation alone.

In “The Sun Within,” I describe how life may have evolved to use the energies of nuclear reactions. Rather than benefitting from external radiation sources like Chernobyl fungi, I suggest that living organisms deliberately induce nuclear reactions within their cells. For example, nuclear fusion could be enabled by bringing atomic nuclei into close proximity through repeated enzyme movements. Electrons emitted in beta decay could be funnelled into the election transport chains in mitochondria, our cells’ “energy powerhouses.”

Nuclear reactions internal to cells would generate energies of similar magnitude and forms (e.g., gamma and beta rays) as those experienced by Chernobyl fungi. But life could have evolved to have far greater control of these energies, such as by limiting their frequency of occurrence, or by targeting them for specific uses.

The remarkable ability of Chernobyl fungi to exploit ionizing radiation points to the need for a broader investigation of atomic biophysics—how nuclear reactions might supplement the energy of life.