FIGURE 1 

Schematic illustration of the consequences of gene deletion on the organism's growth rate. (A) The growth rate following the deletion of an enzyme-encoding gene often drops, but after many generations may recover to a new optimal value not very different from the original one (red line). The optimal growth rate before and after the deletion is predicted by FBA (black and green dotted lines). The blue line indicates the predicted buffering effect of additional gene deletions: by deleting appropriately selected additional genes, the suboptimal growth rate shortly after gene deletions is higher than without the rescue deletions. (B–E) The effect of rescue deletions on the fluxes of a metabolic network, where M₁ ... M₄ represent metabolites and the width of the arrows represents the strength of individual fluxes.