Transformation in Penicillium chrysogenum.

An auxotrophic mutant of Penicillium chrysogenum with a DNA rearrangement that affects the trpC region has been transformed to the Trp+ phenotype by using a plasmid that contains the trifunctional wild-type gene. A frequency of 40-80 transformants per microgram of input DNA was usually achieved. A low frequency of plasmid integration at the recipient mutated trpC gene was detected; however, most of the transformants integrated the plasmid DNA elsewhere into the genome. Some of the transformants contain multiple rearranged copies of the vector integrated in a tandem fashion.