Mem essential amino acid solution

Pseudomonas aeruginosa strain UCBPP-PA14 and Acinetobacter baumannii strain ATCC 17978 were the ancestral strains used in the evolution experiments (75 (link)– (link)77 (link)). A. baumannii ATCC 17978 was propagated for 10 days in minimal medium to preadapt it to the medium conditions prior to the evolution experiment. The minimal medium used in the evolution experiments consisted of an M9 salt base (0.1 mM CaCl₂, 1.0 mM MgSO₄, 42.2 mM Na₂HPO₄, 22 mM KH₂PO₄, 21.7 mM NaCl, 18.7 mM NH₄Cl), 11.1 mM glucose, 20-ml/liter minimal essential medium (MEM) essential amino acid solution and 10-ml/liter MEM nonessential amino acid solution (catalog numbers 11130051 and 11140050; Thermo Fisher), and 1 ml/liter each of trace elements A, B, and C (catalog numbers 99182CL, 99175CL, and 99176CL; Corning). In addition, dl-lactate (catalog number 72-17-3; Sigma-Aldrich) was added to the P. aeruginosa medium to a final concentration of 10 mM in order to generate the approximate nutrient concentrations present in the cystic fibrosis lung environment (78 (link)). All cultures were grown in 18- by 150-mm glass tubes containing 5 ml of minimal medium and incubated at 37°C in a roller drum (30 rpm).