A RAPID METHOD FOR DETECTION OF CLOSTRIDIUM-THERMOCELLUM BY FIELD-EFFECT TRANSISTOR-BASED IMMUNODETECTION

We propose a method for immunodetection of anaerobic bacteria, which h as been developed using Clostridium thermocellum cells. The analysis i ncludes the reaction of specific antibodies with cells in suspension o r after covalent immobilization of cells on porous photo-activated mem branes, and subsequent the revelation of bound specific antibodies by the conjugate of protein A and horseradish peroxidase, and the measure ment of peroxidase activity with a pH-sensitive field-effect transisto r. The measured parameter was the initial rate of pH change in the per oxidase reactions. A specially prepared substrate mixture (1 mM o-phen ylenediamine, 0.1 mM ascorbic acid, 1 mM hydrogen peroxide) ensured th e measurement of the peroxidase label at concentrations of about 10(-1 2) M. The proposed method made it possible to estimate the concentrati on of C. thermocellum within a range of 10(4)-10(7) cells/ml. The syst em is a basis for a FET-based portable instrument for immunodetection of cells.