Fig. 4.

Phenomenological two-state view of E. coli carbon-limited growth. a Respiration and fermentation phenotypes as characterized by the multi-objective optimal states on the Pareto front of E. coli’s metabolism. The respiration phenotype has a larger yield (smaller q) and larger specific protein costs, while the fermentation phenotype carries lower yields (higher q) and smaller cost. b Growth rate (μ) versus carbon-intake cost w_C as obtained from the phenomenological two-state model discussed in the text (see Supplementary Text, Note 4). For each w_C, the optimal phenotype is the one for which μ is largest. The switch from the fermentation to the respiration phenotype occurs when w_C matches the extra protein cost required by respiration