Fluorescence microscopy. For standard microscope examination, cells were grown to early logarithmic phase in minimal medium complemented with 0.2% glucose. After 2 hours, 5 µM IPTG

or 100 mM arabinose was added, incubated for two hours and cells were fixed on a slide with polylysin. The setup used for fluorescence microscopy consisted of a Zeiss Axioplan2e (Carl Zeiss, Jena, Germany) equipped with a 100× alpha-Plan Fluar objective (NA 1.45) and differential interference contrast (DIC). Images were acquired using a Photometrics CoolSNAP HQ Camera (Roper ScientiWc, Tucson, USA). Fluorescence was excited with a helium lamp Inhibitors,research,lifescience,medical and appropriate filter sets were used to adjust excitation and emission wavelengths. The setup was controlled by the Metamorphs v6.2 program (Universal Imaging Corporation, Downingtown, USA). Bright field images were acquired Inhibitors,research,lifescience,medical as single planes using t DIC. All fluorescence images were taken from single focal planes and scaled using Metamorphs scale image command. All GFP fusions were taken with 1 sec acquisition time. From all cultures, at least 100 cells were controlled. For unspecific cell wall staining, Inhibitors,research,lifescience,medical the cells were incubated with 4µM FM4-64 for 10 min at RT. 4. Conclusions E. coli tends to produce acetate during high cell density fermentation. Acetate production takes place when the rates of carbohydrate

transport and glycolysis exceed a critical value. Many attempts have been performed to couple carbohydrate uptake rates to metabolic flux in order to avoid overflow mechanisms. The sgrRST system provides new regulatory tools to artificially modify glucose uptake rates Inhibitors,research,lifescience,medical GSK1349572 according to biotechnological needs. Clearly, further fundamental research efforts are necessary to adapt and optimize the sgrRST system as an instrument for fine-tuning carbohydrate Inhibitors,research,lifescience,medical uptake in biotechnological applications. Acknowledgments We gratefully acknowledge Anna-Katharina Göhler, Elisabeth Gabor and Jürgen Heinisch for helpful discussions, Katrin Fänger for excellent technical support and Lucille Schmieding for help with the manuscript. This work was financially

supported by the German Ministry of Education and Research through the FORSYS-program (grant FKZ 0315285C to K. Jahreis). Supplementary Tryptophan synthase Files Supplementary File 1 Supplementary Material (PDF, 58 KB) Click here for additional data file.(58K, pdf)
Bacteria are often used as microbial cell factories for delivering functional biomolecules with industrial or pharmaceutical interest. As most of these bioprocesses are metabolically demanding, it is critical to understand the physiological behavior of these organisms and to characterize their metabolic capabilities. Many studies have demonstrated that, under stressful conditions, their metabolic activities are not growth-related, which results in lower biomass yields and productivity [1,2].