Radiation-hungry fungi could clean up waste
Last Updated: Wednesday, May 23, 2007 | 2:15 PM ET
CBC News
Scientists have found some fungi can turn radiation into an energy source for spurring growth, a discovery that could prove useful in cleaning up radioactive sites or provide a food source on future space missions.
Fungi have been long known to feast on a menu that other life forms would consider indigestible: plastic, asbestos and cardboard, to name a few. Fungi have also been known to consume radioactive material, a dietary ability found in bacteria such as Deinococcus radiodurans.
But the ability of fungi to break down the radiation and convert it into energy is a previously undiscovered trait.
Researchers at the Albert Einstein College of Medicine at Yeshiva University also connected the ability to convert radiation to the amount of melanin present in fungi.
Melanin is a dark pigment also found in human skin that helps protect us from the sun's ultraviolet rays.
"Just as the pigment chlorophyll converts sunlight into chemical energy that allows green plants to live and grow, our research suggests that melanin can use a different portion of the electromagnetic spectrum — ionizing radiation — to benefit the fungi containing it," said Ekaterina Dadachova, associate professor of nuclear medicine and microbiology and immunology at Einstein and the lead author of a study published Wednesday in the scientific journal PLoS One.
Senior author Arturo Casadevall said he began the study five years ago when he read on the web that a robot sent into the Chornobyl power plant in Ukraine after the 1986 meltdown had returned with samples of black, melanin-rich fungi growing on the reactor's walls.
The researchers exposed several types of fungi to radiation from the decay of cesium-137, an isotope of cesium created as a byproduct of the nuclear fission of uranium and plutonium.
Two types of fungi — one of which was induced to create melanin and another where the pigment occurred naturally — both grew significantly faster when exposed to radiation levels 500 times higher than those we are normally exposed to on Earth. Fungal strains without melanin did not grow any faster when exposed to radiation.
The researchers said fungi that convert radiation could be useful for nuclear cleanups or in outer space, where ionizing radiation is more prevalent.
"Astronauts might be able to rely on fungi as an inexhaustible food source on long missions or for colonizing other planets," said Dadachova.
