SOB Medium

To a one liter bottle add:

1. 20 g Bacto-Tryptone
2. 5 g Yeast Extract
3. 0.5 g NaCl

Dissolve in 950 ml DI. Add 10 ml of 250 mM KCl. Adjust pH to 7.0 using 5 N NaOH (~200 ul). Adjust volume to 1 liter and autoclave. Just before use add 5 ml of sterile 2M MgCl2.