Summary: The intra- and extracellular concentrations of a-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 a-amylase productivity, whereas the residence time of the intracellular a-amylase pool was approximately the same for the three strains. At high glucose concentrations there was a low constitutive synthesis of a-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 a-amylase. Finally, from immunoblots, both a glycosylated and an unglycosylated a-amylase have been detected.
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