Fig. 2.

A schematic representation of the central carbon metabolism of E. coli (adapted from ref. 35). Experimental fluxes are labeled v1–v24 and are measured in the direction of the arrows. Note that in some cases, flux flows in the opposite direction and is measured by a negative value. The thick arrows highlight the short alternative pathway (v19–v18–v21) predicted by ROOM in response to the knockout of pyk (marked with an X) under medium-glucose growth conditions. Major changes in flux along this pathway were experimentally determined (21). See the supporting information for the mapping between the experimental fluxes and model reactions. (Note that unlabeled reactions such as 6PG to KDPG were not experimentally measured.)