Comparison of the solution space spanned by elementary modes. A: Wild type network of E. coli (36,590 EMs). B: Wild type network of S. cerevisiae (9,844 EMs). The biomass yield on glucose is plotted against the IPP yield on glucose [C-mol/C-mol] for all computed elementary modes. Elementary modes on the axes represent modes producing either only biomass (x-axis) or only IPP (y-axis). Theoretical maximal IPP yields at zero growth as well as with biomass formation are highlighted.