Thursday, May 24, 2007

Super Fungi Feed on Radiation

Art © Steve Ditko. Space Adventures © current copyright holder.

Scientists have long assumed that fungi exist mainly to decompose matter into chemicals that other organisms can then use. But researchers have found evidence that fungi possess a previously undiscovered talent with profound implications: the ability to use radioactivity as an energy source for making food and spurring their growth.

Those fungi able to "eat" radiation must possess melanin, the pigment found in many if not most fungal species. But up until now, melanin's biological role in fungi—if any--has been a mystery.

"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," says Dr. Dadachova.

The research began five years ago when Dr. Casadevall read on the Web that a robot sent into the still-highly-radioactive damaged reactor at Chernobyl had returned with samples of black, melanin-rich fungi that were growing on the reactor's walls.

Fungi exposed to levels of ionizing radiation approximately 500 times higher than background levels grew significantly faster (as measured by the number of colony forming units and dry weight) than when exposed to standard background radiation. link
Ionizing Radiation Changes the Electronic Properties of Melanin and Enhances the Growth of Melanized Fungi. Ekaterina Dadachova, et al. PLoS ONE 2(5): e457.