TABLE 3.
Selenium speciation (as percentage) in R. sphaeroides cells grown with selenium oxyanions, based on least-squares fitting of selenium K X-ray absorption near-edge spectra
| Amt of selenite or selenate added (ppm) | % Selenium speciation
|
R (104) | |||
|---|---|---|---|---|---|
| Se0 | RSeR | SeO32− | Me2SeO2 | ||
| SeO32− (0.86) | 36 (2) | 60 (2) | 4 (1) | 1.5 | |
| SeO32− (104) | 97 (1) | 3 (1) | 3.1 | ||
| SeO42− (0.80) | 13 (2) | 84 (3) | 4 (2) | 3.4 | |
| SeO42− (114) | 15 (1) | 81 (2) | 2 (1) | 2 (1) | 1.0 |
a
Abbreviations are same as for Fig. 1, except that the spectrum of RSeR represents the mean of the spectra of aqueous dimethyl selenide and selenomethionine (see text for details). A value equivalent to three times the estimated standard deviation, obtained from the diagonal element of the covariance matrix, is shown in parentheses after each value. R is a goodness-of-fit parameter, defined as R = Σ(Io − Ic)/n, where Io and Ic are the observed and calculated intensities and n is the number of observations.