CALORIMETRY OF DUAL LIMITATIONS IN YEAST CULTURES

Chemostat cultures of one aerobic fermenting yeast (Saccharomyces cei evisiae) and one aerobic respiring yeast (Kluyveromyces fragilis) have been grown under dual C + N limitation in an isothermal reaction calo rimeter. The dual limitations resulted in uncoupled oxidation of part of the glucose, which enabled the culture to adapt the ratio of nitrog en to carbon consumption rates precisely to the N/C ratio that was fed into the calorimeter. This conclusion has been reached based on the c alorimetric measurements, which reflect uncoupled respiration conspicu ously as abnormal heat yields or ratios of heat release per biomass gr own.