title: Identification of biogenic dimethyl selenodisulfide in the headspace gases above genetically modified Escherichia coli.
abstract: Escherichia coli JM109 cells were modified to express the genes encoded in a 3.8-kb chromosomal DNA fragment from a metalloid-resistant thermophile, Geobacillus stearothermophilus V. Manual headspace extraction was used to collect the gases for gas chromatography with fluorine-induced sulfur chemiluminescence analysis while solid-phase microextraction was used for sample collection in gas chromatography/mass spectrometry (GC/MS) analysis. When grown in the presence of selenate or selenite, these bacteria produced both organo-sulfur and organo-selenium in the headspace gases above the cultures. Organo-sulfur compounds detected were methanethiol, dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide. Organo-selenium compounds detected were dimethyl selenide and dimethyl diselenide. Two mixed sulfur-selenium compounds, dimethyl selenenyl sulfide and a chromatographically late-eluting compound, were detected. Dimethyl selenodisulfide, CH(3)SeSSCH(3), and dimethyl bis(thio)selenide, CH(3)SSeSCH(3), were synthesized and analyzed by GC/MS and fluorine-induced chemiluminescence to determine which corresponded to the late-eluting compound that was bacterially produced. CH(3)SeSSCH(3) was positively identified as the compound detected in bacterial headspace above Se-amended cultures. Using GC retention times, the boiling point of CH(3)SeSSCH(3) was estimated to be approximately 192 degrees C. This is the first report of CH(3)SeSSCH(3) produced by bacterial cultures.
authors.affiliation: Department of Chemistry, Sam Houston State University, Huntsville, TX 77340, USA.
authors.forename: Jerry W
authors.initials: JW
authors.lastname: Swearingen
authors.forename: Danielle P
authors.initials: DP
authors.lastname: Frankel
authors.forename: Derie E
authors.initials: DE
authors.lastname: Fuentes
authors.forename: Claudia P
authors.initials: CP
authors.lastname: Saavedra
authors.forename: Claudio C
authors.initials: CC
authors.lastname: Vásquez
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Chasteen
mesh_terms: D004926:Escherichia coli / Q000737:chemistry* / Q000235:genetics; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D001411:Geobacillus stearothermophilus / Q000737:chemistry / Q000235:genetics / Q000254:growth & development; D008163:Luminescent Measurements / Q000379:methods; D016566:Organoselenium Compounds / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D012680:Sensitivity and Specificity; D013440:Sulfides / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D013997:Time Factors; D014835:Volatilization
chemical_list: D016566:Organoselenium Compounds; D013440:Sulfides; C510799:dimethyl selenodisulfide