"Radiosynthesis" remains an unconfirmed but compelling hypothesis—a fungal alchemy that could turn poison into power.

The Chernobyl Fungus That Eats Radiation

A fungus discovered within the Chernobyl Exclusion Zone, Cladosporium sphaerospermum, has demonstrated the ability to thrive and grow faster in the presence of ionizing radiation. While researchers have proposed a mechanism by which the fungus could convert radiation into energy—termed "radiosynthesis"—this pathway has not been experimentally confirmed.

Discovery and Initial Findings

In the late 1990s, a team led by microbiologist Nelli Zhdanova of the Ukrainian National Academy of Sciences surveyed the Chernobyl Exclusion Zone. The team identified 37 species of fungi within the shelter surrounding the ruined reactor. The samples were dominated by dark, melanin-rich fungi, including Cladosporium sphaerospermum. These samples exhibited high levels of radioactive contamination.

Radiation Resistance and Growth

Subsequent experiments led by radiopharmacologist Ekaterina Dadachova and immunologist Arturo Casadevall of the Albert Einstein College of Medicine showed that exposure to ionizing radiation does not harm C. sphaerospermum. Instead, the fungus demonstrated enhanced growth under such conditions. The experiments also indicated that ionizing radiation alters the behavior of the fungal melanin.

Proposed Mechanism: Radiosynthesis

In a 2008 paper, Dadachova and Casadevall proposed a theory of "radiosynthesis." This theory suggests that the fungus may harvest ionizing radiation and convert it into energy, with melanin acting in a manner similar to chlorophyll in photosynthesis. Melanin also appeared to act as a protective shield against harmful radiation.

Unconfirmed Mechanism and Current Understanding

Scientists have not yet demonstrated carbon fixation that is dependent on ionizing radiation, metabolic gain from ionizing radiation, or a defined energy-harvesting pathway for C. sphaerospermum. The specific mechanism by which the fungus benefits from radiation remains undetermined. It is currently unclear whether the observed interaction is an adaptation that uses radiation as an energy source or a stress response that enhances survival.

Findings from Space Experiment and Other Observations

A 2022 study attached C. sphaerospermum to the exterior of the International Space Station. Sensors indicated that less radiation penetrated through the fungus than through an agar-only control. This study aimed to explore the fungus's potential as a radiation shield and did not aim to confirm radiosynthesis.

Other melanized fungi exhibit varying responses to radiation. The black yeast Wangiella dermatitidis shows enhanced growth under ionizing radiation. In contrast, Cladosporium cladosporioides exhibits enhanced melanin production but not growth under gamma or UV radiation, indicating that C. sphaerospermum's behavior is not universal among melanized fungi.