Microbial enzymatic assay of glucose in serum

Three types of bacteria were immobilized by the calcium alginate gel occlusion method, and a microbial rod using the immobilized microbial membrane was prepared for the determination of glucose. The hydrogen peroxide produced from glucose by microbial enzyme action at pH 7.2 was measured by use of oxidative coupling of 4-chlorophenol and 4-aminoantipyrine catalyzed by mimetic peroxidase (manganese[5,10,15,20-tetrakis(4-sulphophenyl)-21H,23H-porphine]). The method was simple, reliable and inexpensive since expensive and unstable isolated enzymes were replaced by the microbial enzyme and the mimetic enzyme. The linear response range is 4–40 μg ml−1. The relative standard deviation at 40 μg ml−1 (n = 9) was 1.78. Glucose in serum can be determined with recoveries of 97–104%. There was no interference by other biological substances in serum. The rod was used daily over a period of two months.