Bacteria have the capacity to efficiently adapt to environmental changes by sensing the availability of nutrients. Because glucose is one of the most abundant carbon sources in the environment, it is the most favored carbohydrate in most organisms. Although different organisms employ different uptake systems for glucose, many organisms, including yeasts and E. coli, show preferential growth on glucose when presented with mixtures of glucose and other carbon sources. It is known that glucose, sensed by its transporters or metabolizing enzymes, inhibits the uptake of certain other sugars into the cell or represses the synthesis of enzymes required to grow on those alternative carbon sources such as lactose. In most bacteria, glucose and many other carbohydrates are transported via the phosphoenolpyruvate (PEP):sugar phosphotransferase system (PTS). This multi-component system carries out a PEP-dependent transport and phosphorylation of numerous sugars (group translocation; Fig. 1).