Biomethylation of Toxic Metalloids

Thomas G. Chasteen and Verena Van Fleet-Stalder
Department of Chemistry, Sam Houston State University, Huntsville, Texas and
The Texas Regional Institute for Environmental Studies, Huntsville, Texas

100th Texas Academy of Sciences Meeting in Huntsville, Texas
March 6-8, 1997

Work in our research group has centered around sensitive and selective detection of volatile organometalloids that have been produced by microorganisms. Many facultative anaerobic bacteria have shown to be biogenic sources of reduced and methylated compounds of selenium: Dimethyl selenide, dimethyl diselenide and dimethyl selenenyl sulfide are routinely detected in the headspace of many microbes whose growth medium has been amended with oxyanions of Se, selenate and selenite. And furthermore the volatile organometalloids are less toxic then these completely inorganic precursors. Anaerobic phototrophic bacteria have also shown this ability with selenium and tellurium and recently, trimethylantimony [(CH3)3Sb] has been determined in bacterial headspace in cultures grown in our laboratory. A short history of Se, Te, and Sb biomethylation will be discussed and data from time course experiments of cultures amended with these elements will be presented.