SOC medium for phage libraries

20 g tryptone

5 g yeast extract

0.5 g NaCl

186 mg KCl

10 mL MgCl₂ (1 M, sterile)

20 mL glucose (1 M, filter-sterilized)

Bring first 4 ingredients to 1 L total volume with H₂O, stir until dissolved, and titrate to pH 7. Sterilize by autoclaving on liquid cycle for 20 min at 121°C at 15 psi. When cooled, add the last two ingredients. Using aseptic conditions, aliquot into 10-mL portions and store at room temperature.