Extendend Data Figure 2. Growth-rate crossover patterns for various combinations of substrates.

a—d. The growth rate of the titratable LacY strain (Supplementary Figure 1a) grown on lactose and a second substrate (glycerol, maltose, xylose or fructose) as a function of 3MBA concentration. Each plot shows the measured growth rate on lactose only (green diamonds), the growth rate on the second substrate only (orange or red triangles), and the growth rate in the presence of both (pink circles).

e—h. As Panels a—d, but for the titratable PtsG strain (Supplementary Figure 1b) and glucose (green diamonds) instead of lactose.

i. Similar results for the titratable GlpK strain (Supplementary Figure 1c) growing on glycerol (orange triangles), mannose (red diamonds), or both (pink circles).

In all cases (Panels a—i), if the 3MBA concentration is reduced sufficiently, the growth rate on the preferred carbon substrate eventually becomes smaller than the growth rate on the non-preferred one. Yet, the growth rate in the presence of both substrates never drops below the growth rate on the non-preferred one, indicating that the uptake of the non-preferred substrate is induced. In almost all cases, the crossover regime is rather narrow. The glucose-fructose hierarchy is an apparent exception.