A dark fungus containing melanin thrives in highly radioactive environments. They could provide the key to protecting astronauts bombarded by cosmic radiation. What they teach us could also lead to breakthroughs for life here on Earth.
Extremophile “Chernobyl fungi” appeared in radioactive soil around the Chernobyl nuclear accident site. They are “highly melanated,” with the same pigment in human skin, eyes, and hair. It’s a natural sunblock that changes the sun’s energy into heat and protects us from UV radiation.
Similarly, melanotic organisms grow in the radioactive water in active nuclear reactors; scientists aren’t sure how they process the radiation. Unlike other organisms, they are able to avoid mutating, breaking down, or developing cancers.
They know the pigment in these organisms offers some protection, but more than that, Chernobyl fungi are also radiotrophic. They can metabolize energy from radiation like a “dark and dangerous version of photosynthesis,” as Scientific American put it. In other words, they eat radiation.
The fungi move toward radiation and heat sources and can break down radioactive soil particles.
Video about radiotrophic fungi by SciShow:
How Does Melanin Block Radiation?
Human skin contains melanin, but the extremophile fungus, Cladosporium sphaerospermum, can use it in a way we can’t. Melanin allows the fungus to produce food or chemical energy from radiation, possibly through mediating electron transfer in some way, like an “electric transformer,” as nuclear chemists put it.
Scientists have found an enzyme used in melanin synthesis in another fungus, Paecilomyces variottii, which also colonized the Chernobyl site. The enzyme heptaketide naphthopyrone, or Ywa1, is a yellow precursor to melanin. They suspect it may play a role in protecting the fungus and in making food. Possibly, Ywa1 scatters the radiation, preventing harm to the cellular DNA.
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Applications for Extremophile Fungus
Practical applications for the extremophile fungus could include protecting astronauts from cosmic rays with shielding or protective suits, use in sunscreens, and decontaminating radioactive sites. (Which they seem to be doing all on their own.)
Astronauts could grow radiation shielding in space using the melanated fungus, suggests Freethink. But if they can also find a way to harness the energy, it would be a renewable energy source useful anywhere sources of radiation are present.
Given the news of solar flares, one wonders if applications could protect the Space Station or be used in other ways near Earth.
Melanin In Our Skin
If a fungus uses melanin to protect itself from radiation and harvest energy, why can’t we? It’s an outlandish thought, but synthetic biologists have explored similar ideas for many years.
For example, what if humans could be partly photosynthetic? It’s known that some animals can utilize genes or chloroplasts from algae to derive energy. Other animals harvest pigments like carotenoids and xanthopterin to harvest solar energy.
Scientists have injected photosynthetic bacteria into fish, and both continued to live, although the fish weren’t solar-powered as a result. Possibly, humans could one day have photosynthetic green patches to aid in healing wounds.
Since our skin already contains melanin, could we find a way to make it function like melanin in extremophile fungus? If so, how would that affect our ability to travel into deep space?