Pigment helps fungi to 'eat' radiation

Radiation can be used as an energy source by some fungi, according to a report from scientists in the US. 

Arturo Casadevall and his colleagues from Yeshiva University in New York measured the growth of fungi exposed to ionising gamma radiation and discovered that it grew faster than unexposed samples.

This unusual ability seems to depend on the presence of the dark pigment melanin within the fungi, also found in human skin. Using a technique called electron spin resonance (ESR), the researchers observed changes in the electronic properties of melanin in response to radiation. These changes, they suggested, could allow it to shuttle its electrons more readily during metabolic chemical reactions.

Ekaterina Dadachova, the lead author of the study, compared the conversion of radiation into chemical energy by melanin, to green plants’ use of chlorophyll to convert sunlight into a food source. She suggested that melanin simply uses a ’different portion of the electromagnetic spectrum - ionising radiation.’

Casadevall was inspired to begin the research project after he read about a robot, sent into the highly-radioactive damaged reactor at Chernobyl, which had returned with samples of black, melanin-rich fungi that were growing on the reactor’s walls. It now seems likely, according to Dadachova, that the fungi in the contaminated reactor were able to harness the radiation for their growth.

According to Dadachova, this ability could prove useful for the provision of food during manned space missions. ’Since ionizing radiation is prevalent in outer space, astronauts might be able to rely on fungi as an inexhaustible food source on long missions or for colonizing other planets,’ she says.

Victoria Gill