Development of a gene transfer system for Penicillium chrysogenum

We report here the development of an endogenous gene transfer system for the industrially-important Deuteromycete Penicillium chrysogenum, utilising a recombinant plasmid designated pPC-31 to complement a tryptophan — auxotrophic strain. Transformation frequencies in the order of 300–1800 transformants per μg DNA have been obtained, and Southern hybridisation analysis has demonstrated that in the majority of cases, integration is mediated by homologous recombination between pPC-31 and the host genome at the site of the resident mutant allele.