A Fungus at Chernobyl Is Eating the Radiation

Inside one of the most radioactive buildings on Earth, a black fungus is not hiding from the gamma rays. It is growing toward them.

Cladosporium sphaerospermum was first observed on the walls of Chernobyl's destroyed Reactor 4 after the 1986 disaster, a dark, velvety mold thriving precisely where the contamination was highest. Scientists have since documented that it doesn't merely tolerate ionizing radiation; it exhibits radiotropism, meaning it actively steers its growth toward the radiation source. The leading explanation involves melanin, the same pigment that gives human skin its color. In this fungus, melanin appears to absorb ionizing radiation and convert it into chemical energy, a process researchers have named radiosynthesis, by analogy to photosynthesis.

The analogy is apt and the evidence is real: lab studies show that melanin-rich fungi exposed to radiation levels 500 times above normal increased in biomass and accelerated their metabolism. But the precise mechanism remains unconfirmed. Radiosynthesis is still a hypothesis, not a settled pathway. The fungi also still require carbon and nitrogen to survive, so if they're "eating" radiation, they are doing it as a supplement, not a replacement for conventional nutrition.

What's confirmed is stranger than the headline: something is happening at the molecular level in these organisms that we don't fully understand, and it appears to be useful. C. sphaerospermum has already been sent to the International Space Station to test whether it could shield astronauts from cosmic radiation. Researchers are also studying it as a potential bioremediation tool, a living cleanup crew for nuclear contamination sites where conventional methods can't safely go.

The exclusion zone around Chernobyl will remain uninhabitable for roughly 20,000 years. The fungus does not appear to be waiting.

Read the full story at Forbes / Scott Travers, November 2, 2024

Hot Take: The entire framework of biology rests on the assumption that ionizing radiation is something life defends against — and here is an organism that has apparently decided to treat that assumption as a suggestion. The fact that we still can't fully explain the mechanism after nearly four decades of study is either a reminder of how much we don't know, or a very polite way of saying the fungus is ahead of us.