of dimethyl tellurenyl sulfide and methanetellurol
headspace gases above tellurium-amended bacterial cultures using
gas chromatography with fluorine-induced chemiluminescence
detection and mass spectrometric detection
Jerry W. Swearingen*, Manuel A. Araya#, Mary F. Plishker*, Claudia P. Saavedra#, Claudio C. Vasquez#, Thomas G. Chasteen*
*Department of Chemistry, Sam Houston State University, Huntsville, Texas USA, 77341-2117
# Laboratorio de Microbiologia Molecular, Facultad de Quimica y Biologia, Universidad de Santiago de Chile
Presented at the 60th Southwest Regional ACS meeting in Ft. Worth, Texas USA, September 29-October 2, 2004. Talk ENVR 319.
This talk's PowerPoint presentation. (1.0 MB)
Escherichia coli JM109 cells were modified to express genes from a DNA fragment from Geobacillus stearothermophilus V that is believed to encode proteins for methyltransferase activity and tellurium resistance. Later experimentation showed that the modified E. coli cells also have selenium resistance. The modified bacterium was inoculated with 0.01 mM tellurite. Forty-eight to seventy-two hours after inoculation methanetellurol (CH3TeH), dimethyl telluride (CH3TeCH3), dimethyl ditelluride (CH3TeTeCH3), and dimethyl tellurenyl sulfide (CH3TeSCH3) were detected in the headspace using gas chromatography; sulfur chemiluminescence detection or mass spectrometric detection. CH3TeH and CH3TeSCH3 have never been previously detected in the headspace gases above tellurium-amended bacterial cultures. No standards were available for CH3TeH and CH3TeSCH3, therefore a method was developed in order to synthesize these organo-tellurium compounds for retention time correlation, boiling point determination, and structural studies using GC-MS. Diluted sulfuric or hydrochloric acid was added to zinc along with small amounts of CH3TeTeCH3 and dimethyl diselenide (CH3SeSeCH3). The headspace gases of this reaction yielded both CH3TeH and CH3TeSCH3 along with traces of the reactants CH3SeSeCH3 and CH3TeTeCH3. DL-dithiothreitol was also tested as a reducing agent. Manual headspace extraction and solid phase micro extraction (SPME) was separately used in the detection of headspace gases. The question about whether the mixed species tellurium compound (CH3TeSCH3) is a product of bacterial metabolism or a product of either an exchange or disproportionation reaction between different tellurium and sulfur organic species will be covered. The synthesis of dimethyl tellurenyl selenide (CH3TeSeCH3) will also be discussed along with a description of future experiments involving the detection of this compound in the headspace gases above bacterial cultures amended with both toxic selenium and tellurium salts.