SOB

Summary
SOB Medium. Used in growing bacteria for preparing chemically competent cells

Ingredients

 * 0.5% (w/v) yeast extract
 * 2% (w/v) tryptone
 * 10 mM NaCl
 * 2.5 mM KCl
 * 20 mM MgSO4

Per liter:
 * 5 g yeast extract
 * 20 g tryptone
 * 0.584 g NaCl
 * 0.186 g KCl
 * 2.4 g MgSO4

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 prior to use. This requires approximately 25 ml of 1M NaOH per liter.

15/10 medium
Growth of competent TOP10 cells in Example 2 of the Bloom05 patent is performed in 15/10 broth, which is similar to SOB:


 * 1.5% yeast extract
 * 1% Bacto-Tryptone
 * 10mM NaCl
 * 2mM KCl
 * 10 mM MgCl2
 * 10 mM MgSO4

Source
Adapted From:

F. Ausubel et al., Short Protocols in Molecular Biology (John Wiley & Sons, ed. 4, 1999) pg. A1-36

Trivia
SOB supposedly stands for super optimal broth.