Radiation tolerant bacteria could be even more effective at clearing up nuclear waste through natural processes than previously thought.

Studies from the group have shown that land contaminated with radioactive waste can also be cleaned up by bacteria that convert soluble forms of radionuclides, such as uranium, to insoluble forms that are less hazardous and mobile.  However, for this to be useful, a critical question has needed addressing for some time; whether these naturally occurring activities are killed off by radiation associated with the radioactive waste.

Now, in a new paper published in Applied and Environmental Microbiology, we have shown that radiation could actually allow certain microbes to thrive, rather than killing them all.  Despite gamma radiation doses relevant to the bioremediation of radionuclide contaminated land and the geodisposal of radioactive waste, biogeochemical processes in sediment microcosms were not restricted as expected. Rather, significant and surprising shifts in phylogenetic composition of microbial communities were observed, including the emergence of Geobacter sp. associated with enhanced levels of Fe(III)-reduction.

The study, highlighted by the journal as an ‘article of significant interest’, suggests that low doses of radiation could provide the basis of novel ecosystems in engineered environments and the deep biosphere. Indeed, processes such as this could make microbial communities more effective in the cleaning up of contaminated land or in contributing to the safety of radioactive waste disposal in the long-term.

Our very own Prof. Jon Lloyd said: “This could provide a new, and very useful extra layer of protection when we are trying to dispose of nuclear waste. There are advanced plans on how this can be done safely, often involving the use of concrete and steel barriers, but there is recognition that at some point in the distant future these barriers will be breached.

“But by assessing the ability of these useful microbes to survive radiation stress, we can be more confident that the waste will remain locked-up for very long periods of time (many thousands of years), helped by a naturally evolving “biobarrier”.  Before this research, the assumption was that the radiation would probably kill off the bacteria that we are studying, but it seems that is not the case. It is potentially a very important finding for the nuclear industry, and illustrates how resilient biology can be!”

Ash Brown.

Brown AR, Boothman C, Pimblott SM, Lloyd JR. 2015. The impact of gamma radiation on sediment microbial processes. Applied and Environmental Microbiology, 81(12): 4014–4025; doi:10.1128/AEM.00590-15.

Articles of Significant Interest Selected from This Issue by the Editors. Applied and Environmental Microbiology, June 2015, 81(12): 3899; doi:10.1128/AEM.01265-15

Thanks to Sam Wood (Media Relations Officer at the University of Manchester) for preparing the initial press release.