Medium optimization for the production of glucose isomerase from thermophilic Streptomyces thermonitrificans.

A thermophilic strain of Streptomyces thermonitrificans produced a high activity of intracellular glucose isomerase (12 U/ml) when grown in a medium containing 1% (w/v) xylose, supplemented with 2% (w/v) sorbitol as the second carbon source, at 50°C for 16 h. Addition of Mg(2+) enhanced enzyme production but the organism could grow and produce the enzyme in the absence of Co(2+).