Induction and repression of alpha-amylase production in batch and continuous cultures of Aspergillus oryzae.

The intra- and extracellular concentrations of alpha-amylase in Aspergillus oryzae have been measured during batch culture of a wild-type strain and two recombinant strains. The mean intracellular level for the two recombinant strains was about four to five times the level of the wild-type strain. The recombinant strains also had a higher alpha-amylase productivity, whereas the residence time of the intracellular alpha-amylase pool was approximately the same for the three strains. At high glucose concentrations there was a low constitutive synthesis of alpha-amylase, whereas at low glucose concentrations derepression resulted in an increased production rate. Shifts from a glucose- to a maltose-limited chemostat showed that maltose induces both the production and secretion of alpha-amylase. Finally, from immunoblots, both a glycosylated and an unglycosylated alpha-amylase have been detected.