Abstract: | Compared with saccharification in the absence of yeast, simultaneous saccharification and fermentation (SSF) using Trichoderma cellulases and Saccharomyces cerevisiae enhanced cellulose hydrolysis rates by 13–30%. The optimum temperature for SSF was 35°C. The requirement for β-
-glucosidase (β-
-glucoside glucohydrolase, EC 3.2.1.21) in SSF was lower than for saccharification: maximal ethanol production was attained when the ratio of the activity of β-
-glucosidase to filter paper activity was 1.0. Ethanol inhibited cellulases uncompetitively, with an inhibition constant of 30.5 gl −1, but its effect was less severe than that of an equivalent concentration of cellobiose or glucose. No irreversible denaturation of cellulases 1,4-(1,3;1,4)-β-
-glucan 4-glucanohydrolase, EC 3.2.1.4] by ethanol was observed. |