Researchers at the Albert Einstein College of Medicine in Yeshiva University have reportedly found evidence of fungi possessing the ability to use radioactivity as an energy source for making food and spurring their growth.
According to Dr. Arturo Casadevall, chair of microbiology and immunology at Einstein and senior author of the study, this finding could trigger a recalculation of the Earth's energy balance and help feed astronauts.
Scientists have long assumed that fungi exist mainly to decompose matter into chemicals that other organisms can then use.
"The fungal kingdom comprises more species than any other plant or animal kingdom, so finding that they're making food in addition to breaking it down means that Earth's energetics—in particular, the amount of radiation energy being converted to biological energy—may need to be recalculated," says Casadevall.
"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," says Dr. Ekaterina Dadachova, an Associate Professor of nuclear medicine and microbiology and immunology at Einstein and co-lead author of the study.
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.
"I found that very interesting and began discussing with colleagues whether these fungi might be using the radiation emissions as an energy source," says Dr. Casadevall.
To test this idea, the Einstein researchers performed a variety of in vivo tests using three genetically diverse fungi and four measures of cell growth. The studies consistently showed that ionizing radiation significantly enhances the growth of fungi that contain melanin.
Both species grew significantly faster (as measured by the number of colony forming units and dry weight) than when exposed to standard background radiation.
The researchers also carried out physico-chemical studies into melanin's ability to capture radiation.
By measuring the electron spin resonance signal after melanin was exposed to ionizing radiation, they showed that radiation interacts with melanin to alter its electron structure. This is an essential step for capturing radiation and converting it into a different form of energy to make food, they added.