TB buffer for competent cells (Inoue)
SOB Medium. Used in growing bacteria for preparing chemically competent cells
- yeast extract
- 5 g yeast extract (0.5% w/v)
- 20 g tryptone (2% w/v)
- 0.584 g NaCl (10 mM final)
- 0.186 g KCl (2.5 mM final)
- 2.4 g MgSO4 (20 mM final)
Note: Some formulations of SOB use 10 mM MgCl2 and 10 mM MgSO4 instead of 20 mM MgSO4.
SOB medium is also available dry premixed from Difco, 0443-17.
Adjust to pH 7.5. This requires approximately 25 ml of 1M NaOH per liter.
Open Wet Ware
SOB supposedly stands for super optimal broth.