SOB

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(Ingredients)
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*2.4 g MgSO<sub>4</sub>
*2.4 g MgSO<sub>4</sub>
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''Note:'' Some formulations of SOB also include 10 mM MgCl<sub>2</sub>.
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''Note:'' Some formulations of SOB use 10 mM MgCl<sub>2</sub> and 10 mM MgSO<sub>4</sub> instead of 20 mM MgSO<sub>4</sub>.
SOB medium is also available dry premixed from Difco, 0443-17.
SOB medium is also available dry premixed from Difco, 0443-17.

Revision as of 11:28, 9 May 2006

Contents

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.

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.

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