PROTEASE-DEFICIENT MUTANTS OF THE QUORN(R) MYCOPROTEIN FUNGUS, FUSARIUM-GRAMINEARUM A3 5/

Protease-deficient mutants of two highly branched (colonial) mutants o f the Quorn(R) mycoprotein fungus, Fusarium graminearum A3/5, were gen erated by UV mutagenesis. One protease-deficient mutant of each strain was studied in glucose-limited chemostat culture (D=0.17 h(-1), pH=5. 8) with 5 g casein l(-1) added to the medium and they were found to pr oduce no or very little aspartic protease, which is produced by the pa rental strains under the same conditions. In chemostat culture the pro tease-deficient mutants were unstable with respect to lack of proteoly tic activity regardless of whether or not casein (500 mg l(-1)) was in cluded in the medium. At low dilution rate (D=0.07 h(-1)) or at increa sed pH (pH=6.9), the parental strains produced other proteases in addi tion to the aspartic protease. (C) 1998 Federation of European Microbi ological Societies. Published by Elsevier Science B.V.