CHARACTERIZATION OF A PROTEASE DEFICIENT STRAIN OF PENICILLIUM-ROQUEFORTI GENERATED BY HETEROLOGOUS PLASMID INTEGRATION - POTENTIAL USE FORPROTEIN-PRODUCTION

A strain of Penicillium roqueforti was transformed with a plasmid whic h confers resistance to phleomycin. Stable transformants were selected . They all present a high resistance to the antibiotic. Their proteoly tic activity was tested. One transformant is a proteolytic deficient s train unable to degrade casein. It is characterized by a tandem integr ation of the transformant vector in one site of the genome. The extrac ellular proteins profile of the strain reveals the absence of a 43 kDa polypeptide which probably corresponds to the aspartyl protease of Pe nicillium roqueforti. The aspA gene which encodes aspartyl protease is not expressed in the transformant and Southern analyses show that the aspA gene is not disrupted by the transformation vector.