PROTEASE PRODUCTION BY THE THERMOPHILIC FUNGUS THERMOMYCES-LANUGINOSUS

A total of 500 strains of the thermophilic fungus Thermomyces lanugino sus were screened for their ability to produce proteases. A selected s train, T. lanuginosus P-134 showed high enzymatic activity for proteas es. The maximal yield of proteases was obtained with 4% casein, 4% glu cose and 4% yeast extract in submerged culture. The protease system wa s shown to contain at least two protease isoenzymes by SDS-PAGE with g els containing gelatin as protease substrate. The effects of inhibitor s imply that the two enzymes appear to be serine proteases. The crude proteases of T. lanuginosus P-134 displayed unusual properties. The pr oteases were shown to be one of the most thermostable proteases so far isolated in fungi. The proteases were 100% stable at 50 degrees C. Th e half-life at 60 and 70 degrees was approximately 160 min and 60 min, respectively. Temperature optimum of activity was 70 degrees. The cru de proteases were stable over a broad pH range (4-11). Optimum pH of a ctivity was at 5.0 and 9.0.