Effect of exposure to air on hydrolysis in spent medium. The effect of an anaerobic environment was tested by assessing glucose concentrations produced from the hydrolysis of 50 g/L Avicel in spent MTC medium in the presence of A) low ethanol (3 g/L) and B) high ethanol (40 g/L). The glucose production of samples maintained in anaerobic conditions for the course of the experiment (black, closed) was compared with samples transferred to aerobic conditions (blue, open) at 0 hours (circle), 24 hours (square), 48 hours (cross) and 72 hours (triangle). Results indicate exposure to air increased glucose concentrations at all sample time points. Data points represent individual samples but are representative of repeated experiments.