NABIR Researchers Report Uptake of Plutonium by Common Soil Microorganisms


Researchers in BER’s Natural and Accelerated Bioremediation Research (NABIR) Program reported in the June 8 edition of the journal Environmental Science & Technology that commonly occurring microorganisms can take up the radionuclide plutonium (Pu). Dr. Mary Neu and her co-workers at LANL studied Microbacterium flavescens, a relatively common soil microbe that takes up iron as a nutrient by producing siderophores. Siderophores are agents that bind and transport iron into the cell. The researchers found that the microbe can use the same type of siderophores that transport iron as a mechanism to take up and accumulate Pu. While other researchers have previously reported sorption of some forms of Pu to the surfaces of cells, Neu’s work is the first to show unequivocal transport into the cell and to elucidate the mechanism for that transport. Because iron is an essential nutrient for life, iron siderophores are common in bacteria, fungi and even plants, suggesting a major pathway for removal of plutonium from the aqueous phase. The effects of microbes and microbially produced siderophores on plutonium are significant not only for the prediction of the long term fate of such toxics in the environment, but also for the development of novel technologies for bioremediation of plutonium and other actinide elements through removal from the aqueous phase and immobilization in microbial biomass.