Bioreduction of Uranium(VI) Complexed with Citric Acid by Clostridia Affects its Structure and Mobility
Uranium contamination of the environment from mining and milling operations, nuclear-waste disposal, and ammunition use is a widespread global problem. Natural attenuation processes such as bacterial reductive precipitation and immobilization of soluble uranium is gaining much attention. However, the presence of naturally occurring organic ligands can affect the precipitation of uranium. Here, we report that the anaerobic spore-forming bacteria Clostridia, ubiquitous in soils, sediments, and wastes, capable of reduction of Fe(III) to Fe(II), Mn(IV) to Mn(II), U(VI) to U(IV), Pu(IV) to Pu(III), and Tc(VI) to Tc(IV); reduced U(VI) associated with citric acid in a dinuclear 2:2 U(VI):citric acid complex to a biligand mononuclear 1:2 U(IV):citric acid complex, which remained in solution, in contrast to reduction and precipitation of uranium. Our findings show that U(VI) complexed with citric acid is readily accessible as an electron acceptor despite the inability of the bacterium to metabolize the complexed organic ligand. Furthermore, it suggests that the presence of organic ligands at uranium-contaminated sites can affect the mobility of the actinide under both oxic and anoxic conditions by forming such soluble complexes.
- Research Organization:
- Brookhaven National Laboratory (BNL) National Synchrotron Light Source
- Sponsoring Organization:
- Doe - Office Of Science
- DOE Contract Number:
- AC02-98CH10886
- OSTI ID:
- 980045
- Report Number(s):
- BNL--92963-2010-JA
- Journal Information:
- Environmental Science & Technology, Journal Name: Environmental Science & Technology Journal Issue: 22 Vol. 42
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE
54 ENVIRONMENTAL SCIENCES
61 RADIATION PROTECTION AND DOSIMETRY
99 GENERAL AND MISCELLANEOUS
ACTINIDES
AMMUNITION
BACTERIA
BINDING ENERGY
CITRIC ACID
COMPLEXES
CONTAMINATION
ELECTRONS
ENVIRONMENT
LIGANDS
MILLING
MINING
MOBILITY
NATURAL ATTENUATION
PRECIPITATION
REDUCTION
SEDIMENTS
SOILS
URANIUM
URANIUM 228
USES
VALENCE
WASTES
national synchrotron light source