Abstract
The production of α-amylase activity in the yeast Schwanniomyces castellii strain 1402 is repressed in the presence of the non-metabolizable glucose analogue, 2-deoxy-glucose. Selection for resistance to 2-deoxy-glucose after treatment with ethyl methane sulphonate (EMS) or UV light has yielded mutants displaing increased α-amylase activities. One such mutant, S. castellii strain 1436, was found to exhibit constitutive α-amylase activity in glucose-containing medium. This constitutive enzyme activity was also observed under pilot scale fermentation conditions when the pH was maintained constant at 5.5±0.1. The disaccharide maltose served as a stronger inducer of α-amylase activity than the natural substrate starch in both the wild type (1402) and mutant (1436) strains.
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