COMPARISON OF 2 GLUCOAMYLASES PRODUCED BY ASPERGILLUS-ORYZAE IN SOLID-STATE CULTURE (KOJI) AND IN SUBMERGED CULTURE

Two extracellular glucoamylases (EC 3.2.1.3) of Aspergillus oryzae wer e purified from solid-state culture (S-GA) and from submerged culture (L-GA). The two glucoamylases have different molecular masses, 65 kDa for L-GA; 63-99 kDa for S-GA, and different isoelectric points, 4.2 fo r L-GA; 3.9 for S-GA. Almost all of the enzymatic characteristics of t he two glucoamylases were similar, except for thermal stability, initi al reaction velocity on pullulan and K-m value with soluble starch. Al though L-GA could digest raw starch, S-GA demonstrated little activity with raw starch. Peptide mapping and amino acid composition showed th at L-GA must be encoded by the glaA gene previously cloned as the gluc oamylase-encoding gene from A. oryzae, bat S-GA had a different primar y structure than the deduced glaA product. introduction of multiple co pies of the glaA gene to A. oryzae caused on elevation of glucoamylase productivity of transformant in submerged culture but not in solid-st ate culture. These results suggested that the two forms of glucoamylas es arise from different genes rather than result from proteolytic proc essing after polypeptide synthesis of a single protein.