Purpose

The purpose of this research was, in part, to develop a method for the pre-concentration and extraction of selenocyanate from the liquid cultures of selenium-resistant bacteria using solid-phase extraction and capillary electrophoresis with photodiode array detection. An environmental soil bacterium (130404) growing on a complex medium displayed an inherent resistance to various forms of selenium and had the ability to convert them into elemental and insoluble selenium and into organoselenides. Experiments using ion chromatography-inductively coupled plasma-mass spectrometry indicated that this bacterium was also able to convert small quantities of selenate into selenocyanate. The goal was to develop a method to pre-concentrate selenium species in broth cultures of metalloid resistant bacteria (via solid-phase extraction) and determine the concentration of these chemical species using capillary electrophoresis. Experiments were also carried out to examine the effect of various selenium-containing species on the growth of 130404 and an E. coli clone (1VH) by examining the optical density of the culture over time. Similar experiments were carried out with a Bacillus spp. to determine such factors as nitrate dependence and ampicillin resistance. The headspace of liquid cultures of 1VH and the Bacillus was also examined using solid-phase microextraction and gas chromatography with fluorine-induced sulfur chemiluminescence detection. Both organosulfides and organoselenides were observed in the headspace of selenium-amended cultures, indicating their ability to bioprocess the selenium-containing species.

Experiments also examined the effect of various selenium-containing species on the growth of 130404 and E. coli clone (1VH) by examining the optical density of the culture over time. Similar experiments were done with a Bacillus spp. to determine such factors as nitrate dependence and ampicillin resistance. The headspace of liquid cultures of 1VH and the Bacillus was also examined using solid-phase microextraction and gas chromatography with fluorine-induced sulfur chemiluminescence detection. Both organosulfides and organoselenides were observed in the headspace of selenium-amended cultures, indicating their ability to bioprocess the selenium-containing species.

Keywords: selenocyanate, capillary zone electrophoresis, bacteria, growth medium, solid phase extraction