SELF-CLONING IN FILAMENTOUS FUNGI - APPLICATION TO THE CONSTRUCTION OF ENDOTHIAPEPSIN OVERPRODUCERS IN CRYPHONECTRIA-PARASITICA

The filamentous ascomycete fungus Cryphonectria papasitica naturally s ecretes endothiapepsin, an aspartic proteinase. It is cultured on a co mmercial scale as a source of the milk-clotting enzyme for cheese maki ng. Our objective was to increase enzyme production of an industrial C . parasitica strain by a new technique of self-cloning; it consisted i n the screening for transformants producing higher levels of endothiap epsin and having integrated only the DNA fragment of interest. Such ge netically improved strains that are devoid of any foreign genes should be more readily acceptable for the production of food-grade enzymes.