Extracellular L-glutamate oxidase from Streptomyces sp. Z-11-6: preparation of it and its properties

Mutagenesis induced with nitrous acid and subsequent selection allowed a genetically stable mutant strain, Streptomyces sp. Z-11-6, to be obtained, whose L-glutamate oxidase activity was 40-fold higher than that of the original natural isolate and was as great as 1.6-1.8 units/ml of culture liquid. A procedure for the isolation and purification of the enzyme was developed; the biochemical properties of the enzyme were studied. Out of 20 amino acids tested (including D-glutamate), the glutamate oxidase from Streptomyces sp. Z-11-6 was active only with L-glutamate. This allows the concentration of L-glutamate to be determined in the presence of other amino acids. Calcium chloride at a concentration of 0.1-0.5% promoted the secretion of the extracellular glutamate oxidase.