Simulation of metabolic behavior for optimal cellular growth as a function of oxygen availability, ranging from completely anaerobic fermentation to completely aerobic growth in S. cerevisiae. The range of oxygen uptake rates used in the simulations (orange line, Fig. 1) allows for the characterization of the PhPP's seven phases (P1 - P7) and two lines of optimality (LOgrowth, LOethanol). (a) Growth rate and respiratory quotient (RQ). (b) Secretion profile for acetate, succinate, ethanol, and glycerol.