Vapour line

This medium is the M9 minimal medium described for E. coli K12 in [15] and [26] . It is based on glucose as a limiting carbon source, a phosphate buffer, salts and micronutrients. This medium contains, per liter: 5 g D-glucose (Acros), 1 g NH 4 Cl (VWR Prolabo), 0.5 g NaCl (VWR Prolabo), 6 g Na 2 HPO 4 anhydrous (Acros), 3 g KH 2 PO 4 (Fisher Scientific). The following components are then added separately from a stock solution: 2 mL of 1 M MgSO 4 • 7 H 2 O (Chem-Lab), 1 mL of 0.1 M CaCl 2 (Sigma), 0.3 mL of 1 mM thiamine HCl (Sigma) and 10 mL of trace element solution. This trace element solution contains, per liter:
and 0.18 g of CoCl 2 • 6 H 2 O (Riedel de Haën). This growth medium is sterilized according to the protocol in Nanchen et al. [26] . The different solutions containing glucose, salts and phosphate buffer are separately autoclaved (VWR Vapour Line) and mixed afterwards. Then, the separately sterilized micronutrient solution is added after cooling of this mixture. thiamine HCl is filter sterilized through a 0.2 µm pore size filter (TRP Filtermax) due to thermal instability, as well as the trace element solution, to prevent precipitation of any poorly soluble salts during or after autoclaving.