Phototrophic Bacteria And Selenium, Tellurium And Antimony Compounds

Verena Van Fleet-Stalder, Eser Becer, and Thomas G. Chasteen
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

Unlike most microorganisms, many strains of phototrophic bacteria have been shown to be resistant to oxyanions of selenium and tellurium. These organisms are able to detoxify their environment by reducing and-in some cases-methylating the toxic compounds converting them into insoluble metallic or volatile methylated forms. Six strains of purple nonsulfur bacteria were exposed to varied concentrations of selenite, selenate, tellurite and tellurate while growing. After one week the headspace of these cultures was tested for methylated selenium and tellurium compounds. All six strains were able to produce various methylated selenium compounds when amended with selenium oxyanions; and all cultures turned coal-black from elemental tellurium when amended with tellurium oxyanions. However, only two strains have been found to release dimethyl telluride. Furthermore, the resistance of these strains towards potassium antimonyl tartrate and potassium hexahydroxy antimonate was tested and headspace samples of cultures able to grow in the presence of these two antimony compounds were analyzed for trimethyl stibine.