Figure 5

Overflow metabolism in chemostat cultures at the intermediate growth rate D = 0.3 h^-1. Overflow metabolism occurs in chemostats with high concentration of glucose feed (5.6 mM Glc in the media). The distributions of fluorescence measurements corresponding to PrpsM-gfp, PptsG-gfp, PmglB-gfp, Ppck-gfp and Pacs-gfp are depicted in different colors presenting different replicates. The background fluorescence is plotted in black. High variability in the measurements of PmglB-gfp and Pacs-gfp (upper row) suggests that the chemostats were operated at the threshold of switching to overflow metabolism. Some replicates showed a bimodal distribution of the expression of the acs reporter in chemostats with 5.6 mM Glc in the feed. This suggests the presence of two phenotypic subpopulations with different expression patterns of acs: a first population down-regulates the acs expression (and possibly excretes acetate) and a second population expresses acs (and possibly takes up and utilizes acetate).