Fig. 4. Effects of kLa on cell activity (a) and the relationship between cell activityand ethanol yield (b). Two samples at different aeration rates were withdrawn, andeach sample was measured twice. Diamonds, 0 vvm; squares, 0.005 vvm; triangles,0.010 vvm; crosses, 0.015 vvm; bars, 0.020 vvm; and circles, 0.025 vvm.