Chernobyl's Radiation-Resistant Fungi May Hold Clues for Space Travel and Nuclear Safety
- Gauri Khanna
- 40 minutes ago
- 4 min read
Too long to read? Go for the highlights below.
Black fungi discovered thriving inside Chernobyl's reactor shelter appear to use melanin to interact with ionising radiation, though the exact mechanism remains unproven
Space station experiments confirmed the fungi can block radiation penetration, suggesting potential applications as biological shields for long-duration space missions
Scientists have documented 37 fungal species in the exclusion zone, with melanin-rich varieties dominating the most contaminated areas, yet cannot explain how they harvest energy from radiation
Nearly four decades after the Chernobyl disaster rendered its surroundings uninhabitable for humans, life has not merely returned to the exclusion zone, some organisms appear to have found advantage in the very radiation that keeps people away. On the interior walls of structures surrounding the ruined reactor, scientists have documented a curious phenomenon: black fungi clinging to surfaces where ionising radiation reaches levels lethal to most life forms.
The dominant species, Cladosporium sphaerospermum, presents a puzzle that has occupied researchers since microbiologist Nelli Zhdanova's team from the Ukrainian National Academy of Sciences first surveyed the site in the late 1990s. Their field work identified 37 fungal species within the shelter, with melanin-rich, dark-hued varieties prevailing. C. sphaerospermum not only dominated samples but also exhibited the highest levels of radioactive contamination amongst the specimens collected.
The Radiosynthesis Hypothesis
Ionising radiation strips electrons from atoms which is a process that fractures molecular bonds, disrupts biochemical reactions, and damages DNA. For most organisms, exposure proves catastrophic. Yet when radiopharmacologist Ekaterina Dadachova and immunologist Arturo Casadevall at the Albert Einstein College of Medicine exposed C. sphaerospermum to ionising radiation in controlled experiments, the fungus demonstrated not merely resistance but enhanced growth.
Their 2008 paper proposed a mechanism they termed radiosynthesis, a biological pathway analogous to photosynthesis, wherein melanin might function similarly to chlorophyll in plants. The theory suggests the fungus harvests ionising radiation and converts it to usable energy, whilst simultaneously employing melanin as a protective barrier against radiation's destructive effects. This would represent a fundamentally novel energy acquisition strategy in known biological systems.
The hypothesis gained circumstantial support from a 2022 experiment aboard the International Space Station. Scientists affixed samples of C. sphaerospermum to the station's exterior, exposing them to cosmic radiation's full intensity. Sensors beneath the fungal samples registered lower radiation penetration compared to control dishes containing only agar growth medium, suggesting the organism actively attenuates radiation passage.
What Remains Unknown
Despite these intriguing observations, the fundamental question persists: what precisely is the fungus doing? As engineer Nils Averesch and colleagues at Stanford University note, researchers have failed to demonstrate several criteria essential to confirming radiosynthesis. No experiments have shown carbon fixation dependent on ionising radiation, measurable metabolic gains from radiation exposure, or a defined biochemical pathway for energy harvesting.
The behaviour also lacks universality amongst melanised fungi. Wangiella dermatitidis, a black yeast, exhibits accelerated growth under ionising radiation. Another species, Cladosporium cladosporioides, increases melanin production but not growth rates when exposed to gamma or ultraviolet radiation. This variability suggests the mechanism operating in C. sphaerospermummay represent a specific adaptation rather than a general property of melanin-containing fungi.
Two competing interpretations emerge from available data. The first posits genuine radiosynthesis: an evolved capacity to metabolise high-energy radiation that proves lethal to competitors. The alternative frames the observed behaviour as a sophisticated stress response that enhances survival under extreme conditions without providing metabolic advantage. Current evidence cannot conclusively distinguish between these scenarios.
Practical Applications Under Investigation
The International Space Station experiments led in part by MelaTech founder and John Hopkins University professor Radames Cordero, reflected practical interest beyond theoretical biology. Long-duration space missions face significant challenges from cosmic radiation exposure, which increases cancer risk and can damage electronics. Biological radiation shields incorporating C. sphaerospermum could offer advantages over traditional shielding materials: they self-repair, require minimal mass at launch, and potentially grow during missions to maintain effectiveness.
Terrestrial applications warrant consideration as well. Nuclear facilities require ongoing maintenance in high-radiation environments. Understanding how these fungi neutralise radiation's harmful effects might inform development of biological remediation strategies or protective coatings for equipment and structures.
The phenomenon also challenges assumptions about life's environmental boundaries. If organisms can derive benefit from ionising radiation, whether through true energy harvesting or enhanced stress tolerance, it expands the range of conditions under which biological processes might operate. This bears implications for astrobiology, suggesting potential biosignatures in radiation-rich environments previously considered incompatible with life.
What remains certain is that this unassuming black fungus, thriving where humans cannot safely venture, has developed capabilities that current biological models cannot fully explain.
Whether C. sphaerospermum truly performs radiosynthesis or employs some other mechanism, its existence in Chernobyl's exclusion zone demonstrates life's capacity to adapt to circumstances that would seem, on first principles, prohibitive. The precise nature of that adaptation awaits definitive experimental confirmation: a challenge that continues to occupy researchers nearly 40 years after the disaster that created this unlikely laboratory.
