Improvement in raw-starch-digesting glucoamylase production by electrofusion of Aspergillus niger

By using the protoplasts of auxotrophic strains Aspergillus niger (lys- and arg-), the stable fusants were obtained. An optimal condition of hybrids to form colonies on MM/CM was found at A = 4.5kV/cm, Np = 32, Tp = 62.5 microseconds, T = 0.2s, Cy = 10, D = 3mm, and Ff = 60%. Through observation of the morphology, the size, the DNA content and the activity of glucoamylases, the differences between the fusants and segregants and their parental strains were shown. These results indicated the new possibility for strain improvement in A. niger.