Metabolic enzyme cost explains variable trade-offs between microbial growth rate and yield
Fig 6
Growth rates achieved with two variants of glycolysis.
(a) Glucose- and oxygen-dependent growth rates predicted for wild-type E. coli. Same data as in Fig 4(c), but shown as a heatmap. E. coli can employ two variants of glycolysis: the Embden-Meyerhof-Parnas (EMP) pathway, which is common also to eukaryotes, and the Entner-Doudoroff (ED) pathway, which provides a lower ATP yield at a much lower enzyme demand [21]. (b) A simulated ED knockout strain that must use the EMP pathway. The heatmap shows the relative growth advantage of the wild-type strain (i.e. of reintroducing the ED pathway to the cell). The ED pathway provides its highest advantage at low oxygen and medium to low glucose levels. (c) Growth advantage provided by the EMP pathway. The advantage is highest at glucose concentrations below 10 μM. (d) Comparison between the two knockout strains. Blue areas indicate conditions where ED is more favorable, and red areas indicate conditions where EMP would be favored. The dark blue region at low oxygen and medium glucose levels may correspond to the environment of bacteria such as Z. mobilis, which uses the ED pathway exclusively [50]. The same data are shown as Monod surface plots in Figure 21 in S1 Text.