Growth and enzyme production during continuous cultures of a high amylase-producing variant of Aspergillus oryzae

Growth and product formation by a selected variant of Aspergillus oryzae showing high alpha-amylase production was studied in continuous cultivations carried out at six different specific growth rates, using glucose as the growth-limiting nutrient. The analysis of the steady-state data revealed that the variant and wild-type strains were similar with respect to glucose uptake system and stoichiometric coefficients.

However, the variant was capable of maintaining an enzyme production as high as 40 FAUgDW(-1)h(-1) at a dilution rate of 0.2 h(-1), while the wild-type strain reached a maximum specific alpha-amylase production rate of 17 FAUgDW(-1)h(-1) at a dilution rate of 0.1 h(-1). Using a morphologically structured model originally proposed for the wild-type strain, it was possible to describe enzyme production, biomass formation and glucose consumption after modification of a few parameters to adjust the model to the characteristics of the selected variant.