The mysterious Chernobyl black fungus that appears to feed on 20,000x radiation and may one day protect astronauts

A strange form of black fungus discovered inside the wreckage of Chernobyl’s exploded reactor has forced scientists to rethink what life can endure, and what it might even consume. First identified in the late 1990s, the mould does not merely survive in one of the most radioactive environments on the planet. Evidence suggests it may actually grow toward radiation and potentially harvest its energy.

The discovery has opened up remarkable possibilities, from bioremediation of nuclear sites to radiation shielding for astronauts travelling beyond Earth’s protective atmosphere.

A scientist enters Chernobyl and finds life thriving in the shadows

In May 1997, Ukrainian mycologist Nelli Zhdanova stepped into the abandoned ruins of reactor four at the Chernobyl Nuclear Power Plant, a place synonymous with lethal radiation. What she saw defied expectations. Black mould coated ceilings and walls and even crept into metal conduits that once shielded electrical cables.

Outside the plant, wildlife such as wolves and wild boar had flourished during humanity’s absence. Inside, however, radiation levels remained dangerously high, and yet these fungi had colonised the very rooms closest to the explosion site.

Zhdanova had already observed something unusual during earlier soil studies. The fungal hyphae did not scatter randomly across contaminated ground. They appeared to grow toward the radioactive particles themselves, as if drawn to the radiation. Now she found the same behaviour inside the shattered reactor.

Her surveys indicated what she called radiotropism, a phenomenon in which fungal growth seems to orient toward sources of ionising radiation. The finding contradicted long held assumptions that such radiation exists only as a destructive force that shreds DNA and kills living cells.

Her work also positioned the fungi as an unexpected ally in fields ranging from nuclear cleanup to human spaceflight.

A disaster that reshaped science and the zone it left behind

The Chernobyl accident began as a routine safety test in April 1986 and quickly escalated into the worst nuclear disaster in history. Design flaws and operational failures caused a massive explosion, releasing vast quantities of radioactive materials. Radioactive iodine caused acute and long term health effects, including cancer, among exposed populations.

Authorities established a 30 kilometre exclusion zone to protect people from the worst contamination. While humans left, the black mould slowly spread, occupying a world emptied by radiation.

Zhdanova’s surveys also identified thirty six ordinary but diverse fungi that had taken root across the region. Over the next two decades, her research would expand scientific understanding of life in extreme environments. It also captured the attention of Nasa.

Melanin and the mystery of how fungi withstand radiation

Central to the story is melanin, the pigment responsible for the dark colour of the Chernobyl fungi. Melanin also determines hair and skin colour in humans. In both cases, it provides protection. On human skin, melanin absorbs ultraviolet radiation. In fungi, Zhdanova suspected it was shielding cells from ionising radiation, which is far more energetic.

In the ponds surrounding Chernobyl, frogs with higher melanin levels survived better and reproduced more successfully, gradually darkening the population over time.

Melanin does not function like a metal shield that deflects danger. Its disordered structure absorbs radiation and dissipates its energy, while its antioxidant properties help neutralise harmful byproducts created when radiation interacts with biological tissue.

Evidence emerges that the fungi may actually feed on radiation

In 2007, nuclear scientist Ekaterina Dadachova at the Albert Einstein College of Medicine conducted experiments that reinforced Zhdanova’s theory. Melanised fungi grew ten percent faster in the presence of radioactive caesium than identical cultures without radiation. These irradiated fungi also showed signs of enhanced metabolic activity.

Dadachova proposed the concept of radiosynthesis, a biological process in which melanin converts ionising radiation into usable energy, similar to how chlorophyll converts light during photosynthesis. The energy contained in ionising radiation is roughly one million times greater than visible light, making melanin a plausible transducer.

The idea remains a theory because the exact biochemical mechanism has not yet been identified, but researchers have begun isolating proteins and pathways that might underpin it.

Not all melanin rich fungi exhibit radiotropism or increased growth under radiation. For example, only nine of forty seven species collected by Zhdanova reacted in this way. Other studies, including work at Sandia National Laboratories in 2022, found no radiation induced growth changes in some fungal species.

Read More: Airbus Urges Voluntary Checks on 6,000 Planes After Rare Radiation

The fungi thrive again, this time in outer space

In 2018, samples of Cladosporium sphaerospermum, one of the species from Chernobyl, were sent to the International Space Station. Galactic cosmic radiation, a constant stream of high speed charged particles from distant stars, poses one of the greatest health risks to astronauts. It even penetrates lead.

Despite this, the fungi grew significantly faster in orbit. Over twenty six days, their growth rate increased by an average of 1.21 times when exposed to cosmic radiation compared to controls on Earth.

Whether this increase was caused by radiation or by microgravity remains under investigation. Nils Averesch, a biochemist and co author of the study, is now using random positioning machines to simulate zero gravity on Earth to separate the effects.

The researchers also tested the fungi’s shielding capacity. A radiation sensor placed beneath a fungal sample recorded reduced radiation levels as the fungi grew. Even a thin smear of mould provided detectable protection.

Although melanin is a likely contributor, water also plays a major role in absorbing radiation due to its high proton content. Researchers continue to evaluate how each component contributes to shielding.

A new frontier for protecting space travellers

As plans accelerate for Moon bases, Mars missions and deep space exploration, the need for lightweight, effective radiation shielding becomes critical. Traditional materials such as water, glass and metal present significant challenges due to weight. Nasa astrobiologist Lynn J Rothschild has compared transporting them to space to a turtle dragging its shell.

Rothschild’s research has produced experimental fungal based structures that could be grown on planetary surfaces. This myco architecture concept offers a sustainable solution that could be lightweight, regenerating and potentially radiation absorbing.

If radiosynthesis proves real and if melanin rich fungi offer scalable protection, the same organisms that colonised Chernobyl’s ruins might one day help shield astronauts living on the Moon or Mars.

Just as these moulds adapted to one of the most hostile places on Earth, they may one day help humanity take its first secure steps on new worlds.