Radiotrophic fungus

Radiotrophic fungi are fungi that can perform the biological process called radiosynthesis, which means using ionizing radiation as a main energy source to drive metabolization. It has been claimed that radiotrophic fungi have been found in extreme environments such as in the Chernobyl Nuclear Power Plant.

Most radiotrophic fungi use melanin in some capacity to survive. The process of using radiation and melanin for energy has been termed radiosynthesis, and is thought to be analogous to anaerobic respiration. However, it is not known if multi-step processes such as photosynthesis or chemosynthesis are used in radiosynthesis.

Discovery

Many fungi have been isolated from the area around the destroyed Chernobyl Nuclear Power Plant, some of which have been observed directing their growth of hyphae toward radioactive graphite from the disaster, a phenomenon called “radiotropism”. Study has ruled out the presence of carbon as the resource attracting the fungal colonies, and in fact concluded that some fungi will preferentially grow in the direction of the source of beta and gamma ionizing radiation, but were not able to identify the biological mechanism behind this effect. It has also been observed that other melanin-rich fungi were discovered in the cooling water from some other working nuclear reactors. The light-absorbing compound in the fungus cell membranes had the effect of turning the water black. While there are many cases of extremophiles (organisms that can live in severe conditions such as that of the radioactive power plant), a hypothetical radiotrophic fungus would grow because of the radiation, rather than in spite of it.