Biosensor for determination of starch was prepared by fixing a carrier with immobilized enzyme system on the tip of a Clark-type oxygen sensor. Enzymes amyloglucosidase, mutarotase, glucose oxidase and catalase were co-immobilized either on the partially hydrolyzed nylon net or on the activated collagen membrane. In both cases the covalent bond was made in the presence of glutaraldehyde and cyclohexyl isocyanide. The prepared biosensors were compared from the view-point of a specific activity of the immobilized amyloglucosidase, of a linear response area of the biosensor to the substrate concentration, of the pH and temperature of the reaction mixture and of the biosensor stability. Biosensors prepared were used for the determination of starch in the samples of cultivaiting media for the monensin production.