Studies on the Submerged Amylase Production

Part 6. The Variation of Amylase Formation by Black Aspergilli in Acidic Media and in Neutral Media

Abstract

We investigated the variation, of submerged amylase formation by Black Aspergilli in acidic media (added 0.2% of ammonium sulphate; pH of these media was kept at about 2.4 during the incubation) and neutral media (added 0.3% of calcium carbonate to acidic media; pH of these media was kept at about 6.0). In acidic media (Fig. 1) dextrinizing amylase did not appear, but after the weight of mycelium reached to maximum saccharogenic amylase and maltase remarkably increased and saccharifying power came to surpass 40%. Saccharifying power in mycelium was low, but maltase activity in mycelium was considerably high. In neutral media (Fig. 2) dextrinizing amylase was high, but inorease of saccharogenic amylase found in acidic media did not occur and saecharifying power stayed under 10%. Maltase was formed in early period of incubation and decreased, gradually.
Since dextrinizing amylase (α-amylase) is inactivated at pH 2.4, so it was a matter of course that this amylase did'nt appear in acidic, media. But the low activity of saccharogenic amylase in neutral media can not be interpreted by inactivation, for the saccharogenic amylase is stable at pH 6.0 (Table 1). Ca^.. ion also did not inhibit the formation of this enzyme (Table 2) and the weight of mycelium was nearly equal in both media. So we concluded that the acidic cultural environment is necessary for the formation of saccharogenic amylase.
The superior strains for submerged mold amylase belonging to Asp. Usamii group, Asp. awamori., group and Asp. niger group have this property. But Asp. oryzae did'nt grow sufficiently in acidic media and saccharifying power was as low as in neutral media.