EFFECT OF GROWTH-RATE ON ALPHA-AMYLASE PRODUCTION BY STREPTOMYCES SP.IMD-2679

The alpha-amylase of Streptomyces sp. IMD 2679 was subject to cataboli te repression. Four different growth rates were achieved when the orga nism was grown at 40 degrees C and 55 degrees C in the presence and ab sence of cobalt, with an inverse relationship between alpha-amylase pr oduction and growth rate. Highest alpha-amylase yields (520 units/ml) were obtained at the lowest growth rate (0.062 h(-1)), at 40 degrees C in the absence of cobalt, while at the highest growth rate (0.35 h(-1 )), at 55 degrees C in the presence of cobalt, cr-amylase production w as decreased to 150 units/ml. As growth rate increased, the rate of sp ecific utilisation of the carbon source maltose also increased, from 4 6 to 123 mu g maltose (mg biomass)(-1) h(-1). The pattern and levels o f alpha-glucosidase (the enzyme degrading maltose detected intracellul arly in each case, indicate that growth rate effectively controls the rate of feeding of glucose to the cell, and thus catabolite repression .