Effect of different sugars on expression of the cit operons. A) Genetic organization of E. faecalis cit metabolic operons. PcitHO, promoter of the citHO operon composed of CitH (Me2+-citrate transporter) and CitO (GntR transcriptional regulator); PcitCL promoter of the citCL operon composed of OadHDBA (oxaloacetate decarboxylase membrane complex), CitCDEFXG (citrate lyase and accessory proteins) and CitM (soluble oxaloacetate decarboxylase). O1 and O2 binding sites of the activator CitO. B and C) Influence of diverse PTS and non-PTS sugars on the expression of PcitHO-lacZ and PcitCL-lacZ fusions. JHB2 (JH2-2/pTCV-PcitHO), JHB6 (JH2-2/pTCV-PcitCL), CL1 (CL14/pTCV-PcitHO) and CL2 (CL14/pTCV-PcitCL) were grown in LBC and LBC supplemented with 30 mM initial concentration of different sugars. Levels of accumulated β-galactosidase activity were measured 7 h after inoculation. Error bars represent standard deviation of triplicate measurements.