SOLUBILIZATION OF PLUTONIUM HYDROUS OXIDE BY IRON-REDUCING BACTERIA

The removal of plutonium from soils is challenging because of its stro ng sorption to soils and limited solubility. Microbial reduction of me tals is known to affect the speciation and solubility of sparingly sol uble metals in the environment, notably iron and manganese. The simila rity in reduction potential for alpha-FeOOH(s) and hydrous PuO2(s) sug gests that iron-reducing bacteria may also reduce and solubilize pluto nium. Bacillus strains were used to demonstrate that iron-reducing bac teria mediate the solubilization of hydrous PuO2(s) under anaerobic co nditions. Up to similar to 90% of the PuO2 was biosolubilized in the p resence of nitrilotriacetic acid (NTA) within 6-7 days. Biosolubilizat ion occurred to a lesser extent (similar to 40%) in the absence of NTA . Little PuO2 solubilization occurred in sterile culture media or in t he presence of a non-iron-reducing Escherichia coil. These observation s suggest a potentially attractive, environmentally benign strategy fo r the remediation of Pu-contaminated soils.