We provide access to an unique collection of primarily Aspergillus strains, which are suitable for research purposes as well as industrial applications. One of our strains has a remarkably low viscosity. Furthermore, we have developed strains that secrete very little other proteins than the one of interest (of both homologous and heterologous origin). In addition, strains with a significantly reduced proteolytic activity have been developed, improving the stability of the protein of interest during the production phase and in relation to shelve life.