The present invention relates to methods of obtaining a mutant cell from a
filamentous fungal parent cell, comprising: (a) obtaining mutant cells of
the parent cell; (b) identifying the mutant cell which exhibits a more
restricted colonial phenotype and/or a more extensive hyphal branching
than the parent cell; and (c) identifying the mutant cell which has an
improved property for production of a heterologous polypeptide than the
parent cell, when the mutant and parent cells are cultured under the same
conditions.