Production of Glucose Isomerase by Streptomyces flavogriseus

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Abstract
A microorganism that produces glucose isomerase was isolated from soil and identified as a strain of Streptomyces flavogriseus . The organism produced a large quantity of glucose isomerase when grown on straw hemicellulose, xylan, xylose, and H 2 SO 4 hydrolysate of ryegrass straw. The organism produced glucose isomerase both intra- and extra-cellularly. The highest level of intracellular glucose isomerase (3.5 U/ml) was obtained in about 36 h by a culture grown on straw hemicellulose; the extracellular enzyme (1.5 U/ml) appeared in cultures grown for about 72 h. About equal levels of enzyme were produced in cultures grown on straw hemicellulose, xylan, xylose, and H 2 SO 4 hydrolysate of straw, but production of the enzyme was drastically reduced when the organism was grown on other carbon sources. As a nitrogen source, corn steep liquor produced the best results. Soy flour extract, yeast extract, and various peptones also were adequate substrates for glucose isomerase production. Addition of Mg 2+ , Mn 2+ , or Fe 2+ to the growth medium significantly enhanced enzyme production. The organism, however, did not require Co 2+ , which is commonly required by microorganisms used in the production of glucose isomerase.