Laboratoire Léon Brillouin

UMR12 CEA-CNRS, Bât. 563 CEA Saclay

91191 Gif sur Yvette Cedex, France


Let's scatter neutrons

Transformation of selenite and selenate by the facultative aerobe - Ralstonia metallidurans CH34
R. Collins, L. Avoscan, M. Carrière, B. Gouget
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The bacteria Ralstonia metallidurans CH34 is a facultative aerobe that has been shown to reduce selenite (SeO32-), by an intracellular process to elemental selenium (monoclinic form). In soils, however, Se is principally found as selenate (SeO42-) as well as selenite. Therefore, the present study examined the kinetics of selenite and selenate uptake, and transformation, by R. metallidurans CH34. The speciation of these oxyanions was followed by two complementary analytical techniques, Se K-edge XANES spectroscopy and HPLC-ICP-MS. It was observed that selenate was reduced into selenite and then organic selenium such as the amino acid Se-methionine, but not into elemental selenium. It was also found that the reduction of selenite to elemental Se progressed via organic intermediates. These results report a fundamental microbiological process that potentially influences the biogeochemical fate of Se in soils. 
#422 - Last update : 03/25 2005


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