Effect of different glucose concentrations on the expression of cit promoters in a CitO constitutive genetic background. A and B) JHB15 (JHB11/pTCV-PcitHO) and JHB16 strains (JHB11/pTCV-PcitCL) were grown in LBC (circle) or LBC supplemented with different initial concentrations of glucose: 0.25% (square), 0.5% (up-pointing triangle) and 1% (down-pointing triangle). The corresponding open symbols indicate the remaining glucose concentration in the culture medium (right axis). The levels of accumulated β-galactosidase activity were measured at the time points indicated in the figure. Error bars represent the standard deviation of triplicate measurements. C) Western blot analysis was performed in the complemented CitO deficient strain (JHB11), that was cultivated for 6 h in LB medium supplemented with citrate 1% (LBC) or citrate 1% plus glucose 1% (LBCG).