Lb miller medium

All assay experiments were performed in the Escherichia coli strain 3.32 (lacZ13(Oc) lacI22 λ⁻el4- relA1 spoT thiE1; Yale CGSC #5237), transformed chemically, while standard DNA cloning was performed in NEB 5-alpha Competent E. coli (huA2 Δ(argF⁻lacZ)U169 phoA glnV44 φ80Δ(lacZ)M15 gyrA96 recA1 relA1 endA1 thi-1 hsdR17; New England Biolabs) and library construction was performed in electrocompetent E. coli 3.32 cells. Cells were grown in LB Miller Medium (Fisher Scientific) or M9 Minimal Medium (6.8 g L⁻¹ Na₂HPO₄, 3.0 g L⁻¹ KH₂PO₄, 0.5 g L⁻¹ NaCl, 1.0 g L⁻¹ NH₄Cl, 2 mM MgSO₄, 100 μM CaCl₂; Millipore Sigma) supplemented with 0.2% (w/v) casamino acids (VWR Life Sciences), 1 mM thiamine HCl (Alfa Aesar). LB Miller + Agar (Fisher Scientific) was used for selection when cloning. Antibiotics and ligands were used as appropriate. Antibiotics used were: chloramphenicol (25 μg mL⁻¹; VWR Life Sciences), kanamycin (35 μg mL⁻¹; VWR Life Sciences), and carbenicillin (100 μg mL⁻¹; Teknova). Ligands used were: fructose (Arcos Organics), d-ribose (Arcos Organics), and isopropyl-β-d-thiogalactoside (IPTG; Millipore Sigma). All ligands in this study were used at a concentration of 10 mM.

Liquid cultures were grown at 37 °C with aeration, unless otherwise indicated, in either LB Miller medium (Fisher Scientific) or in minimal A medium54 containing 0.2% glucose, 0.1% casamino acids and the indicated concentration of MgSO₄. For routine growth on solid medium, LB or minimal medium containing bacteriological grade agar (Fisher Scientific) was used. The antibiotics ampicillin, kanamycin, chloramphenicol and spectinomycin were used at concentrations 50–100, 25, 20–25 and 50 μg ml⁻¹, respectively. The antibacterial peptide C18G (Anaspec) was added to a final concentration of 9 or 7 μg ml⁻¹, as indicated. The lac and trc promoters were induced with the indicated concentrations of β-isopropyl-D-thiogalactoside (IPTG) and the araBAD promoter was induced with 30 mM arabinose.