[Isolation and characterization of mutants of Aspergillus niger deficient in extracellular proteases]

Several mutants of Aspergillus niger 3.795, deficient in extracellular protease expression, have been isolated and characterized biochemically after in vitro UV-mutagenesis of conidiospores and selected by halo-screening on the gelatin/casein plate and skim milk plate. Extracellular proteolytic activities of 3.795-1-23 and 3.795-1-30 are 5.4% and 8.4% of the parental strain and these strains may be used as the host for efficient expression of foreign proteins.