FIG. 1.

Lactose consumption rates (gray columns) during fermentation for recombinant S. cerevisiae strains T1 and T1-E at 30°C and for K. lactis strain CBS2359 at 30 and 18°C. The zero-trans uptake rates at 20 mM lactose (white columns) and the glucose-stimulated rates (striped columns) are also shown for direct comparison. The assay temperature (the same as that in fermentation) is indicated. Lactose consumption rates are the average values with standard deviations (SDs) of 2 to 5 independent fermentations. Zero-trans rates are the averages with SDs of 3 to 8 determinations with independently grown yeast suspensions. Glucose-stimulated rates are the zero-trans lactose (20 mM) uptake rates obtained after optimal preincubation of the yeast suspension with 27 mM glucose (single experiments with T1 and T1-E and averages with SDs of 2 to 3 independent experiments with K. lactis).