The composition of the low Cl- minimal medium was, per liter: 1.25g(NH4)2SO4, 1.15g KH2PO4, 0.5g MgSO4.7H2O, 0.5g NaCl, 30g glucose.1H2O, 0.001 gthiamine–HCl, 2ml of trace elements solution and 0.2 ml silicone-based antifoaming agent (BDH,Poole,UK). The composition of the trace elements solution was described in Verduyn et al. [1].

-----------References-------------
[1] Verduyn, C., Postma, E., Scheffers, W.A., van Dijken, J.P., 1992. Effect of benzoic acid on metabolic fluxes in yeasts: a continuous-culture study on the regulation of respiration and alcoholic fermentation. Yeast 8 (7), 501–517

Metabolite extraction procedure - metabolites were extracted in 75 % boiling ethanol (3 min, 90 ºC) as described in Taymaz-Nikerel et al. [1]. Before extraction, 100 µl of 100% U–13C-labeled cell extract was added as internal standard.
Measurement of intracellular met ... abolite concentrations - metabolites of the glycolysis, TCA cycle and PPP were quantified with Isotope Dilution Mass Spectrometry (IDMS) as described by van Dam et al. [2] and Wu et al. [3]. The concentrations of the nucleotides were also analyzed with IDMS. Further details of the applied LC–ESI–MS/MS procedure have been described elsewhere [4].

-----------------References----------------
[1] Taymaz-Nikerel, H., deMey,M., Ras,C., tenPierick,A., Seifar,R.M., vanDam,J.C., Heijnen, J.J., vanGulik,W.M.,2009. Development and application of a differential method for reliable metabolome analysisin Escherichia coli. Analytical Biochemistry 386 (1), 9–19. http://doi.org/bk5b8m
[2] van Dam,J.C.,Eman,M.R.,Frank,J.,Lange,H.C.,vanDedem,G.W.K., Heijnen,S.J., 2002. Analysis of glycolytic intermediates in Saccharomyces cerevisiae using anion exchange chromatography and electrospray ionization with tandem mass spectrometric detection. Analytica Chimica Acta 460 (2), 209–218. http://doi.org/ck9bk6
[3] Wu, L.,Mashego,M.R.,vanDam,J.C.,Proell,A.M.,Vinke,J.L.,Ras,C., van Winden, W.A., vanGulik,W.M.,Heijnen,J.J.,2005.Quantitative analysis of the microbial metabolome by isotope dilution mass spectrometry using uniformly 13C-labeled cell extracts as internal standards. Analytical Biochemistry 336, 164–171. http://doi.org/dp4h5k
[4] Seifar, R.M.,Ras,C., vanDam,J.C.,van Gulik,W.M., Heijnen,J.J., van Winden,W.A., 2009. Simultaneous quantification of free nucleotides in complex biological samples using ion pair reversed phase liquid chromatography isotope dilution tandem mass spectrometry. Analytical Biochemistry 388 (2), 213–219. http://doi.org/cpxjw9