DEVELOPMENT OF A SIMPLE DETECTOR FOR MICROBIAL-METABOLISM, BASED ON A POLYPYRROLE DC RESISTOMETRIC DEVICE

A simple device for the detection of metabolic effects was constructed based on a conducting polymer (polypyrrole) coated with an agarose layer containing immobilised yeast cells. A galvanostatic potentiometric method was used to measure the resistance of the sensor, thus minimising interferences from fluctuations in solution conductivity. The resulting biosensor was used as a simple indicator of yeast metabolism. It responded within 20 minutes to increases in the glucose concentration by decreased resistance (40% per 5 g/l). When the metabolism was inhibited by a toxic substance the response disappeared. The device could be reconditioned by washing off the layer with hot water, followed by the application of a new agarose layer with fresh cells. Because the manufacture of the device is simple and the measuring principle is uncomplicated, it is specially suited for mass production for quick field tests.