Thermostable glucose isomerase production by some bacteria and streptomyces

Out of 75 microbial isolates, screened for the production of extracellular acidic and thermostable glucose isomerases, 8 Streptomyces and 5 bacterial isolates exhibited glucose isomerase activity. The enzyme production varied between 0.01 -0.13 IU mL⁻¹ in Streptomyces spp. and 0.02 - 0.29 IU mL⁻¹ in bacterial isolates. Four Streptomyces spp. J, F, A and O produced considerable amount of enzyme at pH 5 without Co²⁺ ions. The enzyme production was higher in medium containing wheat bran than xylose as carbon source. The enzymes produced by Streptomyces spp. were optimally active at 70°C. The glucose isomerases from Streptomyces spp. strain J and F had pH optima between 6.0 and 6.5, and did not require Co²⁺ for activity while from strains, A and O were neutral to alkaline in nature and attained maximum yield in 72-96 h.