Anaerobic Biotransformation and Mobility of Pu and of Pu-EDTA [electronic resource].
- Washington, D.C. : United States. Dept. of Energy. Office of Science, 2009.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
- Physical Description:
- 21 kb : digital, PDF file
- Additional Creators:
- Washington State University
United States. Department of Energy. Office of Science
United States. Department of Energy. Office of Scientific and Technical Information
- The enhanced mobility of radionuclides by co-disposed chelating agent, ethylenediaminetetraacetate (EDTA), is likely to occur only under anaerobic conditions. Our extensive effort to enrich and isolate anaerobic EDTA-degrading bacteria has failed. Others has tried and also failed. To explain the lack of anaerobic biodegradation of EDTA, we proposed that EDTA has to be transported into the cells for metabolism. A failure of uptake may contribute to the lack of EDTA degradation under anaerobic conditions. We demonstrated that an aerobic EDTA-degrading bacterium strain BNC1 uses an ABC-type transporter system to uptake EDTA. The system has a periplasmic binding protein that bind EDTA and then interacts with membrane proteins to transport EDTA into the cell at the expense of ATP. The bind protein EppA binds only free EDTA with a Kd of 25 nM. The low Kd value indicates high affinity. However, the Kd value of Ni-EDTA is 2.4 x 10^(-10) nM, indicating much stronger stability. Since Ni and other trace metals are essential for anaerobic respiration, we conclude that the added EDTA sequestrates all trace metals and making anaerobic respiration impossible. Thus, the data explain the lack of anaerobic enrichment cultures for EDTA degradation. Although we did not obtain an EDTA degrading culture under anaerobic conditions, our finding may promote the use of certain metals that forms more stable metal-EDTA complexes than Pu(III)-EDTA to prevent the enhanced mobility. Further, our data explain why EDTA is the most dominant organic pollutant in surface waters, due to the lack of degradation of certain metal-EDTA complexes.
- Published through SciTech Connect.
- Type of Report and Period Covered Note:
- Final; 12/15/2004 - 12/31/2008
- Funding Information:
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