Mutation was caused in a strain belonging to Aspergillus, with the goal of cultivating, without using recombinant DNA techniques, a strain of Aspergillus having improved productivity of a variety of industrially-applicable enzymes. Said mutation resulted in a strain of Aspergillus having a large-scale genome duplication of at least 900 kb, said strain having high productivity of a variety of enzymes necessary for the production of soy sauce, such as protease. This strain allows efficient production of soy sauce and various other food products.
