The effect of proteases on the synthesis of glucoamylase by mutants of Aspergillus niger C.

Out of 1230 cultures grown from conidia of the strain Aspergillus niger C, which were previously treated with mutagens, 6 mutants were selected, 5 of which were characterized by considerably lower or lack of proteolytic activity than the parent strain. It was observed that glucoamylase activity and protein synthesis in the mutants examined were directly proportional to the rate of their proteolytic activity. From electrophoretic analysis it was found that in some protease-free mutants or with strongly reduced activity of this enzyme one or two glucoamylase fractions out of four occurring in the parent strain were absent.