A continuous fermentation technique for studying the kinetics of sugar uptake by baker's yeast.

1. Solutions of glucose, maltose or other sugars were pumped at controlled rates into a yeast suspension and the extracellular sugar concentration was determined. The technique was especially suitable for studying the kinetics of fermentation at low rates of sugar utilization. At high rates the fermentation system was unstable. 2. Glucose fermentation was fitted by a model in which a diffusion barrier with first-order kinetics is interposed between the environment and the site of hexokinase. 3. Aerobic conditions affected the fermentation enzyme system but not the diffusion mechanism. 4. The kinetics of maltose fermentation at low rates approximated to those of the hydrolysis of maltose by the enzyme maltase, as studied in suspensions of broken cells.