Here's a possible solution to both the energy crisis and what to do with highly radioactive waste from nuclear reactors: use the radiation as food.

It sounds like something out of a comic book, although scientists already know that fungi will eat asbestos, jet fuel, and plastic. It has also been shown to decompose hot graphite in the ruins of the Chernobyl power plant, which melted down in 1986. The plant's release of large amounts of radiation appears to have attracted black hordes of fungi. But how does it work?

According to Ekaterina Dadachova and her colleagues at the Albert Einstein College of Medicine, in New York City, the fungi Cryptococcus neoformans and two other species use melanin, also a pigment found in human skin, to transform radiation into energy to use as food for growth. Researchers believe that melanin is present to protect fungi from stress, such as radiation, and that certain species use this molecule for metabolic reactions. Dadachova's lab discovered that exposure to radiation caused the melanin in these species to change shape, increasing its ability to impact metabolism and growth. The results appear in Public Library of Science (PLoS).

Dadachova tells me in an e-mail that the most amazing aspect of the finding is that this process is an alternative to photosynthesis, "with melanin playing the role of chlorophyll and ionizing radiation; the role of visible light." Melanin converts the energy from the radiation into chemical energy used by the fungi, she says. "The mechanism of this process needs to be established. It took at least two decades and the work of several research groups to determine the mechanism of photosynthesis."

This suggests that nature itself has produced yet another "alternative energy" scenario that is completely unexpected.

The uses of this discovery could range from a disposal method for nuclear waste to a food source for long space voyages during which fungi could grow using radiation from outer space, although future astronauts may not find fungi very appetizing. Dadachova suggests that the fungi might be used as a biofuel to be grown in high-altitude regions where radiation is prevalent and nothing else can grow. Does this mean that one day huge fungi farms on the slopes of the Andes or the Himalayas will provide us with fuel for our cars, along with fungi steaks for astronauts heading to Mars?

One other interesting aspect for humans: using melanin raises the possibility that this chemical also converts radiation from the sun into food for our skin cells, but only in minute amounts.

Citation:
E. Dadachova et al., "Ionizing radiation changes the electronic properties of melanin and enhances the growth of melanized fungi." PLoS ONE. 2007 May 23;2:e457.

Article in News@Nature.com:
Ledford, Heidi, "Hungry fungi chomp on radiation," published online: 23 May 2007