Researchers reveal fungi role in war fields

Fungi may have an important role to play in the fate of potentially dangerous depleted uranium left in the environment after recent war campaigns, according to a new report from researchers within the College of Life Sciences.

Led by Professor Geoffrey Gadd, head of the Division of Molecular and Environmental Biology, the research found evidence that fungi can "lock" depleted uranium into a mineral form that may be less likely to find its way into plants, animals or the water supply.

"This work provides yet another example of the incredible properties of microorganisms in effecting transformations of metals and minerals in the natural environment," said Professor Gadd.

He added that the testing of depleted uranium ammunition and its recent use in Iraq and the Balkans has led to contamination of the environment with the unstable metal.

Depleted uranium differs from natural uranium in the balance of isotopes it contains. It is the by-product of uranium enrichment for use in nuclear reactors or nuclear weapons and is valued for its very high density. Although less radioactive than natural uranium, depleted uranium is just as toxic and poses a threat to people.

In the study, published in the prestigious journal "Current Biology," the researchers found that free-living and plant fungi can colonise depleted uranium surfaces and transform the metal into uranyl phosphate minerals.

These minerals are capable of long-term uranium retention which may help prevent uptake of uranium by plants, animals and microbes and prevent the spent uranium from leaching out into the soil.

"We have shown for the first time that fungi can transform metallic uranium into minerals, which are capable of long-term uranium retention," the study concluded. "This phenomenon could be relevant to the future development of various remediation and revegetation techniques for uranium-polluted soils."

Professor Gadd's research was funded by the Natural Environment Research Council.