Oral Presentation #29

Identification of Organoselenium and Organotellurium Compounds in the Headspace of Metalloid-Resistant Bacteria Using Gas Chromatography with Fluorine-Induced Chemiluminescence Detection

Radhika Burra1, Gonzalo A. Pradenas2, Claudio C. Vasquez2, and Thomas G. Chasteen1

1Sam Houston State University, Huntsville, TX, 2Universidad de Santiago de Chile, Santiago, Chile

Headspace analyses of different strains of anaerobic bacteria were performed to find the gas phase concentration of volatile organo-chalcogens in the headspace above bacteria when exposed to toxic oxyanions of Se and Te. Using optical density as a measure of bacterial population, growth rates of these bacteria were also examined. Multiple test tubes of the bacterial cultures were prepared with or without metalloid amendment and analyzed sequentially to follow the time-course production of gases in the headspace. Then these gases were extracted using a solid phase microextraction fiber and injected into a gas chromatograph with fluorine-induced chemiluminescence detection. Analysis was also carried out using gas chromatography-mass spectrometry in an effort to identify the unknown compounds found in the headspace of bacterial cultures amended with different concentrations of metalloids. Unknown chromatographic peaks were detected in the headspace at late elution times using F2-induced chemiluminescence detection. Their elution times, high boiling point, and mass spectra were used to identify the structures of the unknown compounds. This is the first report of the headspace production of dimethyl triselenide, CH3SeSeSeCH3, from a metalloid-resistant bacterium amended with a toxic selenium anion.