On the concrete walls of Chernobyl's reactor number four, something grows that defies the most basic biological logic: black fungi that not only survive ionizing radiation but actively seem to seek it out. This phenomenon is called radiotrophy, and for two decades it has forced us to rethink the limits of what fungal life is capable of metabolizing.
Fungi that grow toward radiation
In 2004, a team led by Ukrainian mycologist Nelli Zhdanova documented something unusual in fungal strains isolated from the Chernobyl exclusion zone: exposed to directional beta and gamma radiation sources, the hyphae of these melanized fungi grew by orienting themselves toward the radioactive source, not away from it. The experiment eliminated carbon as a resource variable, isolating the effect of radiation per se on fungal growth.
Melanin: the molecule that changes under radiation
Three years later, Ekaterina Dadachova's team at the Albert Einstein College of Medicine identified a plausible molecular mechanism. Ionizing radiation alters the electronic structure of melanin—the same pigment that protects our skin from the sun—increasing its ability to transfer electrons. In melanized strains of Cryptococcus neoformans, Wangiella dermatitidis, and Cladosporium sphaerospermum exposed to radiation levels hundreds of times higher than natural background, growth measured in biomass and radioactive carbon incorporation was significantly greater than in non-melanized strains. Melanin, the study suggests, could operate as a kind of biochemical antenna capable of capturing and harnessing radioactive energy.
From the exclusion zone to the International Space Station
The natural question was whether this capability could have applications outside of Earth. In 2022, an experiment cultivated Cladosporium sphaerospermum aboard the International Space Station during a period of cosmic radiation exposure, comparing its growth against a terrestrial control and measuring radiation levels beneath the formed fungal biomass. The fungus grew approximately 1.21 times faster in space than on Earth, and a measurable reduction in radiation was recorded under the fungal layer compared to the control without growth—preliminary evidence that a melanized fungal biofilm could function as a partial radiation shield.
Where research is headed
The interest is not anecdotal: cosmic radiation is one of the main obstacles to long-duration crewed missions, and conventional shielding is heavy and expensive to transport. A biological material capable of self-regeneration and growth using radiation itself as an energy source opens a line of research in space life support biotechnology—utilization of in-situ resources, self-sufficient biomaterials, and, perhaps, fungal architectures for extraterrestrial habitats.
References
- Zhdanova NN, Tugay T, Dighton J, Zheltonozhsky V, McDermott P. Ionizing radiation attracts soil fungi. Mycol Res. 2004;108(Pt 9):1089-1096. PMID: 15506020. DOI: 10.1017/s0953756204000966
- Dadachova E, Bryan RA, Huang X, et al. Ionizing radiation changes the electronic properties of melanin and enhances the growth of melanized fungi. PLoS One. 2007;2(5):e457. PMID: 17520016. DOI: 10.1371/journal.pone.0000457
- Averesch NJH, Shunk GK, Kern C. Cultivation of the dematiaceous fungus Cladosporium sphaerospermum aboard the International Space Station and effects of ionizing radiation. Front Microbiol. 2022;13:877625. PMID: 35865919. DOI: 10.3389/fmicb.2022.877625