Bioavailability of selenium accumulated by selenite-reducing bacteria |
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Authors: | Gerald F Combs Carlos Garbisu Boihon C Yee Andrew Yee Donald E Carlson Nancy R Smith Andrew C Magyarosy Terrance Leighton Bob B Buchanan |
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Institution: | (1) Division of Nutritional Sciences, Cornell University, 14853 Ithaca, NY;(2) Department of Plant Biology, University of California, Berkeley, CA;(3) Earth Sciences Division, Lawrence Berkeley Laboratory, Berkeley, CA;(4) Department of Biological Sciences, California State University, Hayward, CA;(5) Department of Molecular and Cell Biology, University of California, Berkeley, CA |
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Abstract: | The bioavailability of selenium (Se) was determined in bacterial strains that reduce selenite to red elemental Se (Seo). A laboratory strain ofBacillus subtilis and a bacterial rod isolated from soil in the vicinity of the Kesterson Reservoir, San Joaquin Valley, CA, (Microbacterium arborescens) were cultured in the presence of 1 mM sodium selenite (Na2SeO3). After harvest, the washed, lyophilizedB. subtilis andM. arborescens samples contained 2.62 and 4.23% total Se, respectively, which was shown to consist, within error, entirely of Seo. These preparations were fed to chicks as supplements to a low-Se, vitamin E-free diet. Three experiments showed that the
Se in both bacteria had bioavailabilities of approx 2% that of selenite. A fourth experiment revealed that gray Seo had a bioavailability of 2% of selenite, but that the bioavailability of red Seo depended on the way it was prepared (by reduction of selenite). When glutathione was the reductant, bioavailability resembled
that of gray Seo and bacterial Se; when ascorbate was the reductant, bioavailability was twice that level (3–4%). These findings suggest that
aerobic bacteria such asB. subtilis andM. arborescens may be useful for the bioremediation of Se-contaminated sites, i.e., by converting selenite to a form of Se with very low
bioavailability. |
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Keywords: | Selenium bacteria bioavailability chick glutathione peroxidase |
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