The relationship between metabolic flux and evolutionary constraint.(a) The relationship between metabolic flux values and evolutionary constraint Ka/Ks for aerobic growth on glucose. (maximal uptake rate for glucose 15.3 mmol/g dry weight (DW)/h; maximal oxygen uptake 0.2 mmol/gDW/h). Spearman's rank correlation r = -0.30; P = 2.7 × 10-3; Pearson's correlation r = -0.24, P = 1.7 × 10-2. The metabolic fluxes were calculated using flux balance analysis to maximize the cell growth rate. Fluxes more than two orders of magnitude larger than the median non-zero flux - representing large glycolytic fluxes - were excluded from the analysis. (b) The same as (a) but using log coordinates for the metabolic flux magnitude.