Iodide accumulation by aerobic bacteria isolated from subsurface sediments of a 129I-contaminated aquifer at the Savannah River site, South Carolina. Academic Article uri icon

abstract

  • (129)I is of major concern because of its mobility in the environment, excessive inventory, toxicity (it accumulates in the thyroid), and long half-life (16 million years). The aim of this study was to determine if bacteria from a (129)I-contaminated oxic aquifer at the F area of the U.S. Department of Energy's Savannah River Site, SC, could accumulate iodide at environmentally relevant concentrations (0.1 M I(-)). Iodide accumulation capability was found in 3 out of 136 aerobic bacterial strains isolated from the F area that were closely related to Streptomyces/Kitasatospora spp., Bacillus mycoides, and Ralstonia/Cupriavidus spp. Two previously described iodide-accumulating marine strains, a Flexibacter aggregans strain and an Arenibacter troitsensis strain, accumulated 2 to 50% total iodide (0.1 M), whereas the F-area strains accumulated just 0.2 to 2.0%. Iodide accumulation by FA-30 was stimulated by the addition of H(2)O(2), was not inhibited by chloride ions (27 mM), did not exhibit substrate saturation kinetics with regard to I(-) concentration (up to 10 M I(-)), and increased at pH values of <6. Overall, the data indicate that I(-) accumulation likely results from electrophilic substitution of cellular organic molecules. This study demonstrates that readily culturable, aerobic bacteria of the F-area aquifer do not accumulate significant amounts of iodide; however, this mechanism may contribute to the long-term fate and transport of (129)I and to the biogeochemical cycling of iodine over geologic time.

published proceedings

  • Appl Environ Microbiol

author list (cited authors)

  • Li, H., Brinkmeyer, R., Jones, W. L., Zhang, S., Xu, C., Schwehr, K. A., ... Yeager, C. M.

citation count

  • 32

complete list of authors

  • Li, Hsiu-Ping||Brinkmeyer, Robin||Jones, Whitney L||Zhang, Saijin||Xu, Chen||Schwehr, Kathy A||Santschi, Peter H||Kaplan, Daniel I||Yeager, Chris M

publication date

  • March 2011