Production of Dimethyl Telluride and Elemental Tellurium by Bacteria Amended with Tellurite or Tellurate

Rukma S. T. Basnayake, Janet H. Bius, Osman M. Akpolat and Thomas G. Chasteen
Department of Chemistry, Sam Houston State University, Huntsville, Texas, 77341-2117, USA

Applied Organometallic Chemistry, 2001, 15(6), 499-510. AOC's abstract


Abstract

Tellurium Time Course ImageThe purpose of this study was to determine whether a facultative anaerobe, Pseudomonas fluorescens K27, would produce dimethyl telluride when anaerobic cultures were amended with differing concentrations of sodium tellurate and/or sodium tellurite and how that volatile organotellurium production varied over time. Batch bacterial bioreactor experiments were undertaken in order to observe the changes in the headspace of a growth medium solution inoculated with P. fluorescens and amended with tellurium salts. Gas samples were taken from the bioreactor every hour and were analyzed by capillary gas chromatography using fluorine-induced chemiluminescence detection to determine compounds in the headspace. Liquid samples were analyzed by spectrophotometer to determine optical densities which were used as an indicator of cell growth. Verification of the identity of the dimethyl telluride produced in bacterial headspace above a tellurate-amended culture was achieved by comparison with the chromatographic retention time of an authentic (CH3)2Te standard and by gas chromatography/mass spectrometry (see red adjacent figure).

Tellurium Time Course Image

The time course production of dimethyl telluride varied with amendment salts' Te oxidation states and concentrations. Increasing tellurate concentrations caused slower bacterial growth but those cultures reached the stationary phase sooner than cultures amended with tellurite concentrations 10 or 100 times less (see blue adjacent figure). Black elemental Te (Te0) was produced by live cultures amended with Te salts but not by sterile controls. The amount of tellurium in the solid phase (as Te0 and in/or on cells) harvested from replicate, anaerobic cultures of P. fluorescens sampled after 92 hours of incubation was approximately 34%.


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