Effect of growth temperature on the externalization and localization of α-amylase inBacillus stearothermophilus

The synthesis and localization of α-amylase were studied in Bacillus stearothermophilus AN002 at 40, 45, 50 and 55 °C and also during early exponential, late exponential and stationary phases of growth. The extracellular α-amylase synthesis was highes at 50 °C and at stationary growth phase. Accumulation of intracellular α-amylase was observed in cells grown at 40 °C and was distributed in all the cell fractions. At 50 and 55 °C the cell did not have α-amylase in the protoplasm or protoplamic membrane. The synthesis and externalization of extracellular enzyme are two processes and the externalization is controlled by growth temperature and cell age.