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Researchers at the Albert Einstein College of Medicine (AEC) have found evidence
that certain fungi possess another talent beyond their ability to decompose matter:
the capacity to use radioactivity as an energy source for making food and spurring
their growth.
Detailing the research in Public Library of Science ONE, AEC's Arturo Casadevall
said his interest was piqued five years ago when he read about how a robot sent
into the still-highly-radioactive Chernobyl reactor had returned with samples
of black, melanin-rich fungi that were growing on the ruined 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,"
explained Casadevall.
Casadevall and his co-researchers then set about performing a variety of tests
using several different fungi. Two types - one that was induced to make melanin
(Crytococcus neoformans) and another that naturally contains it (Wangiella dermatitidis)
- were exposed to levels of ionizing radiation approximately 500 times higher
than background levels. Both of these melanin-containing species grew significantly
faster than when exposed to standard background radiation.
"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 co-researcher Ekaterina Dadachova.
Investigating further, the researchers measured the electron spin resonance
signal after melanin was exposed to ionizing radiation and found that radiation
interacts with melanin to alter its electron structure. This, they believe,
is an essential step for capturing radiation and converting it into a different
form of energy to make food. Until now, melanin's biological role in fungi -
if any - had been a mystery. Interestingly, the melanin in fungi is no different
chemically from the melanin in our skin, leading Casadevall to speculate that
melanin could be providing energy to skin cells.
And radiation-munching fungi could be on the menu for future 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," noted Dadachova.
