Fate of selenate and selenite metabolized by Rhodobacter sphaeroides.
Cultures of a purple nonsulfur bacterium, Rhodobacter sphaeroides, amended with approximately 1 or approximately 100 ppm selenate or selenite, were grown phototrophically to stationary phase. Analyses of culture headspace, separated cells, and filtered culture supernatant were carried out using gas chromatography, X-ray absorption spectroscopy, and inductively coupled plasma spectroscopy-mass spectrometry, respectively. While selenium-amended cultures showed much higher amounts of SeO(3)(2-) bioconversion than did analogous selenate experiments (94% uptake for SeO(3)(2-) as compared to 9.6% for SeO(4)(2-)-amended cultures from 100-ppm solutions), the chemical forms of selenium in the microbial cells were not very different except at exposure to high concentrations of selenite. Volatilization accounted for only a very small portion of the accumulated selenium; most was present in organic forms and the red elemental form.
Van Fleet-Stalder
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Chemistry Department and Texas Research Institute for Environmental Studies, Sam Houston State University, Huntsville, Texas 77341, USA.
Chasteen
T G
TG
Pickering
I J
IJ
George
G N
GN
Prince
R C
RC
D002849:Chromatography, Gas / Q000379:methods; D003470:Culture Media / Q000737:chemistry; D012242:Rhodobacter sphaeroides / Q000254:growth & development / Q000378:metabolism*; D064586:Selenic Acid; D018036:Selenium Compounds / Q000378:metabolism*; D018038:Sodium Selenite / Q000378:metabolism*; D013057:Spectrum Analysis / Q000379:methods
D003470:Culture Media; D018036:Selenium Compounds; D018038:Sodium Selenite; D064586:Selenic Acid