Further evidence for the existence of a bottleneck in the metabolism of Saccharomyces cerevisiae

The growth physiol. of S. cerevisiae strains H1022 and Whi2+ was studied in aerobic batch and continuous (chemostat) cultures. Results from the measurement of biomass and medium components (off-line) together with O2, CO2, and heat measurements (online) were used to explore the existence of overflow or bottleneck metab. as opposed to catabolite repression (Crabtree effect) in these strains. Chemostat expts. indicated that specific O2 uptake rate (qo2) was linearly related to the diln. rate (D) at values below the crit. diln. rate (Dcrit), becoming const. above Dcrit, which is in agreement with the bottleneck theory. However, batch culture expts. indicated negligible O2 consumption during the initial glucose growth phase, the culture exhibiting purely anaerobic metab. The bottleneck theory would propose that qo2 has a const. (max.) value under these conditions. The results suggest that while the bottleneck theory can be adequately used to describe chemostat growth of S. cerevisiae, some other control mechanism must be operating under conditions of high glucose concns., such as those initially prevailing in the batch culture expts. [on SciFinder (R)]