Iodide accumulation by aerobic bacteria isolated from subsurface sediments of a 129I-contaminated aquifer at the Savannah River site, South Carolina.
Appl Environ Microbiol
; 77(6): 2153-60, 2011 Mar.
Article
em En
| MEDLINE
| ID: mdl-21278282
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 (â¼16 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 µM 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 µM), 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 µM 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.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Bactérias Aeróbias
/
Sedimentos Geológicos
/
Radioisótopos do Iodo
País/Região como assunto:
America do norte
Idioma:
En
Ano de publicação:
2011
Tipo de documento:
Article