Radiotrophic fungus is found at sites of nuclear disasters, and appears to use radiation as an energy source for life.
Learn more about this unique organism and quiz yourself at the end.
What is Radiotrophic Fungus?
All living things need energy in order to grow and thrive. This energy, which originates from the sun, is harnessed by plants and stored in the form of sugars. Members of the animal kingdom like us then eat the energy-rich molecules in plant matter and we grow and thrive as a result. Members of kingdom Fungi do things a little differently, especially one in particular.
While fungi typically absorb their nutrition from other living organisms, one fungus has a way of surviving that seems to be straight out of a sci-fi movie. It is called ‘radiotrophic fungus’, and it appears to gain energy from a highly unusual source: ionizing radiation.
You may hear the word ‘radiation’ and think danger. Although we are bombarded on a daily basis by normal levels of the sun’s radiation, there are much worse types. Ionizing radiation is the kind to avoid, found at nuclear waste sites which are fortunately not frequented by people. At high levels, this radiation causes cancer and possibly death.
So how can an organism possibly use this form of energy to live? In this lesson, learn more about the way in which the tough and adaptable radiotrophic fungus uses radiation.
Radiotrophic Fungus at Chernobyl
When the nuclear reactor at Chernobyl melted down in 1986, extremely dangerous levels of ionizing radiation were emitted. Every living thing in the vicinity either fled or succumbed to the devastation.
So scientists were intrigued when they returned to the site and found life in the form of black fungus covering the walls of the reactor. And it wasn’t just a sparse few, but entire colonies had taken up residence and were happily thriving. It was clear that these fungi were not only spared damage from the radiation, but were somehow using it to their advantage.The question became, what made this fungus special and able to survive this high level of radiation and use it to grow? Let’s take a closer look at fungi as we explore this strange phenomenon.
- First of all, fungi are heterotrophic. This means that they cannot make their own food through photosynthesis like plants do.
- Second, fungi are decomposers, attaching themselves to other living organisms and absorb their nutrients. You have undoubtedly found mushrooms eating their way through damp fallen logs deep in the forest. It was clear that the radiotrophic fungi were not absorbing nutrition this way as they were growing on the cement walls.
As scientists further investigated, they found that the radiotrophic fungi had a common feature. They were all dark in color, indicating large concentrations of the pigment melanin. Melanin (Greek for ”black”) is also found in our skin, with higher concentrations producing darker skin colors. If you enjoy a luxuriously dark tan in the summer, you have plenty of melanin. Melanin acts as a natural sunblock, absorbing the sun’s ultraviolet rays and protecting the skin cells. So was the melanin somehow responsible for the utilization of radiation in these fungi?To better understand, a team of scientists led by microbiologist Arturo Casadevall performed a set of experiments in which they exposed black fungus as well as albino varieties to high levels of radiation.
Sure enough, those black fungi which were exposed to the highest levels of radiation grew the most. So a theory quickly developed, stating that the melanin had some function in harnessing the energy from this otherwise deadly radiation.It is still not clear to scientists exactly what role melanin plays in this whole process. One school of thought is that melanin is analogous to the green pigment chlorophyll in the harnessing of energy. It is chlorophyll in plants that captures the sun’s energy to store it in plants. Some scientists believe that melanin somehow captures ionizing radiation and converts it to chemical energy for the use of the fungus. Others believe that perhaps the high levels of melanin simply protect the fungi from being harmed, thus allowing them to grow faster.
Uses for Radiotrophic Fungus at Fukushima
Another nuclear disaster happened in 2011 in Fukushima, Japan. Similar to Chernobyl, ionizing radiation was released in deadly amounts. This time, scientists have been contemplating the use of radiotrophic fungus to help in the cleanup of this mess. Because the fungi will absorb the radiation from the soil, they can be planted in the area and then later harvested and disposed of as nuclear waste.
Although this would be a very long process, it would decrease the amounts of radiation continuing to seep out in that area.
Radiotrophic fungus is an organism that appears to use ionizing radiation as an energy source. This fungus has been found at sites of nuclear disasters, growing and thriving. Radiotrophic fungus is dark in color, indicating large amounts of the pigment melanin. It is thought that melanin is instrumental in the conversion of radiation into energy for the fungus.
Scientists are considering the use of this fungus in the cleanup of nuclear waste.