Preliminary Studies of a Bacterial Sulfate Electrode

A bacterial electrode for sulfate was developed by coupling a strain of the bacterium Desulfovibrio desulfuricans with a sulfide selective electrode. This bacterium reduces sulfate to sulfide by a complex multistep enzymatic reaction sequence. The response of this sensor to sulfate is Nernstian in the concentration range of 4 × 10−5 to 7 × 10−4 M. The electrode functions for a period up to 10 days when stored in growth medium under a nitrogen atmosphere. However, it is necessary to keep the sensor in an oxygen-free environment at all times, because oxygen irreversibly inhibits the required enzymes. Although this limits the practical utility of this sensor, alternative configurations for a more practical analytical system are proposed.