FIGURE 1:

Physiology of yeast cultures grown in nitrogen-limited batch and chemostat cultures. (A) When normalized for total nitrogen concentration, the biomass yield is the same regardless of nitrogen source. Values are determined by regression analysis of cell yield, measured using a Klett colorimeter, in batch cultures containing different concentrations of nitrogen. Error bars represent 95% confidence interval of the regression coefficient. (B) Approach to steady-state kinetics for glutamine- and proline-limited chemostats. Each chemostat culture was inoculated with 10⁶ cell/ml and monitored over an 80-h period. Experimental measurements for proline (black triangles) and glutamine (red circles) are in good agreement with a mathematical model of the chemostat (lines).