Determination of Sulfite Ion by Using Microbial Sensor

Chemoautotrophic and aerobic bacterium Thiobacillus thioparus TK-m, which has sulfite oxidation pathways, was used for the development of sulfite ion sensor. The sensor consists of an oxygen electrode and T.thioparus immobilized between two nitrocellulose membranes. Since T.thioparus could not be cultivated In the medium containing sulfite as sulfur source. T.thioparus grown in the thiosulfate containing mediun was used for the experiment. The selectivity for sulfite was gradually increased during the use as sulfite sensor. After 6 days, the response to thiosulfate became approximately 10% of that of sulfite. When the sensor was applied to the sulfite determination in batch system, calibration curve showed the linearity in the concentration range between 4 μM and 280 μM.