Abstract

The effect of environmental factors on glucose isomerase productivity of Saudi Arabia isolated Streptomyces albaduncus was studied. During growth of the tested microorganism in the basal medium at 30°C, the glucose isomerase production reached the maximum level (6530 U/L) after 96 h incubation period. Irrespective of the carbon source, replacement of xylose with different carbohydrate did not increase the enzyme productivity. On the other hand, the highest enzyme productivity was obtained when corn steep liquor (2.0%, w/v) and yeast extract (1%) were used as nitrogen sources. Also, the optimum initial pH for maximum growth and enzyme productivity was 7. Further improvement in the glucose isomerase production was obtained after the addition of 0.01% (w/v) DL-isoleucine to the culture medium. Accordingly, optimization of the environmental condition associated with increase in the glucose isomerase enzyme productivity from S. albaduncus up to 15328 U/L which is approximately 2.3 more times as compared to that obtained under the initial condition. Finally, a promising production of glucose isomerase (14100 U/L) at large scale level was achieved by cultivation of the tested strain in the optimum environmental conditions using laboratory fermentor of 14 L.

Key words: Glucose isomerase, fermentation, environmental condition, Streptomyces albaduncus.