FIG. 1.

Optical densities at 660 nm (O.D.660 nm) (●) and concentrations of glucose (○) and ethanol (□) in aerobic, pH-controlled batch cultures of C. utilis (A), Z. bailii (B), and S. cerevisiae (C). Cultures were grown at pH 3.0 on a synthetic medium (22) supplemented with 20 g of glucose per liter. In all experiments, the dissolved oxygen concentration remained more than 30% of air saturation. Data from two independent replicate experiments differed by less than 10%.