Fig. 4. Effects of kLa on cell activity (a) and the relationship between cell activity and ethanol yield (b). Two samples at different aeration rates were withdrawn, and each sample was measured twice.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.