[Production of mutants with an increased alpha-amylase synthesis]

A mutant characterized by elevated biosynthesis of alpha-amylase was obtained as a result of a three-stage induced selection using nitroso compounds. Changes of mutagens in the course of selection stages and the establishment of their effective doses causing the maximum accumulation of mutations yielded the mutant which produced 2.5 times more alpha-amylase than the parent strain of Aspergillus oryzae 762. The induced variability of the mutant can be registered on a solid growth medium and provides the high activity of alpha-amylase.