Metabolic enzyme cost explains variable trade-offs between microbial growth rate and yield
Fig 2
Metabolic strategies in E. coli metabolism.
(a) Network model of core carbon metabolism in E. coli. Each Elementary Flux Mode (EFM) represents a steady metabolic flux mode in the network, scaled to a unit biomass flux. Reaction fluxes defined by the EFM max-gr are shown by colors. In our reference conditions—i.e. high extracellular glucose and oxygen concentrations—this EFM allows for the highest growth rate among all EFMs. Some of the cofactors in the model are not shown. (b) Statistics of biomass-producing EFMs. (c) Spectrum of growth rates and yields achieved by the EFMs. The labeled focal EFMs are described in Table 1, and their flux maps are given in Figures 25-30 in S1 Text. Pareto-optimal EFMs are marked by squares; the Pareto front is shown by a black line. The plot reveals a positive correlation between growth rate and yield, despite the inevitably negative correlation among Pareto-optimal EFMs. See Figure 24 in S1 Text for a detailed view of the Pareto front and how it was sampled.