Can fungi feed on ionising radiation?

Chris Smith asked biologist and author Tom Ireland...

Tom - In the 1980s, there were scientists working in the destroyed reactor at Chernobyl, where absolutely nothing grows. Except, they found several species of black mould like fungi growing on the walls where the radiation levels were just absolutely off the charts. And these fungi weren't just managing to survive in there, but they seemed to be thriving. They were growing towards the most powerful radiation. And the further tests even suggested they were using the radiation as an energy source, in a similar way to how plants use sunlight to grow. And this is all down to melanin, which is this amazing family of pigments that protect us and mammals and all kinds of animals from UV radiation. And this seems to be completely central to protecting the fungi from these crazy levels of radiation and actually helping them use it to their advantage.

Tom - So as well as just being very exciting research, there's this idea that you could use these fungi and melanin to help protect people from radiation. So for example, when they receive radiotherapy, you could have some kind of agent that contains a special form of melanin that's able to protect the rest of the body from the radiation. And the scientists are also looking at how this could be used to protect people in space. So making space suits from melanin or making buildings on a Martian colony from this fungi, so it grows itself and it's radio protective, that would be a cool idea. One of the scientists who's involved in this research, the starting point is to make little tiny melanin space helmets for mice, and bombarding them with radiation to see if these little astronaut helmets protect them from radiation.

Chris - The most fascinating story I heard about life from radiation, it was a while ago now, about 10 years ago, a lady called Lisa Pratt. She had been working with people going deep down gold mines in South Africa. And they had discovered in one of these mines a pool of water, which you could prove by looking at the composition of the water, had not been in contact with the world for up to 120 million years. But what was extraordinary about this pool of water is it was thronging with bacteria. And if you've got a bubble of water that hasn't had any contact with the outside world for 120 million years, but there's life flourishing in it, you have to ask the question, well, what's it feeding on? It must be eating something. And when they unpicked this, they realised that there are in those rocks enormous numbers of uranium atoms, which are breaking apart radioactively, spitting out these alpha particles, radiation, this is busting apart water molecules and making them into a reactive form of water, which was then attacking minerals in the rocks and liberating sulphur compounds that a whole group of bacteria could then consume. And in turn, those bacteria would feed other bacteria. And so they had a whole community of microbes all surviving because of radiation in the rock. And their argument is, well if they can survive down there, kilometres underground, living off uranium, there's no reason why they couldn't have similar life processes going on in planets elsewhere in the solar system and beyond.

Tom - And that probably tells us quite a lot about potential ways that life started on earth as well, where there wasn't much organic material around to eat. And these strange ways of making energy and growing were probably the ways that life got started in the first place.