J. Bius and T. G. Chasteen

Department of Chemistry
Sam Houston State University
Huntsville, Texas 77341-2117

Bioreactor experiments of 2.7 L volume were carried out using a selenium-resistant bacterium, Pseudomonas fluorescens K27 amended with 10 mM selenite as the sodium salt. After growing the culture into the stationary phase (anaerobically at 30 degrees C), samples were harvested from the bioreactor and separated into solid and liquid phases. Selenium was determined in each phase following their separation by centrifugation and decantation. The method to detect selenium was hydride generation atomic absorption spectrometry. Seven samples taken from 4 different bioreactor cultures show an average of 7.9% (±2.8) conversion of added Se to the precipitated form, that is, elemental Se or on/in harvested cells. The balance remained in the supernatant.