Heat stability of the secreted cellulolytic enzymes. Aliquots of the culture supernatants from fungi grown on microcrystalline cellulose were incubated for one hour at 70°C before measuring the filter paper degrading activity (see “Methods”). Activities are given as percent remaining activity after one hour incubation at 70°C percent compared to control samples incubated at 50°C. The experiment was repeated three times. Error bars indicate standard deviations. Stars next to bars indicate that the activity at this pH was significantly lower than the highest activity (1 star: P < 0.05, 2 stars: P < 0.01, 3 stars: P < 0.001, Student’s T-test). See Table 1 for abbreviations of fungal names.