SOB
From OpenWetWare
Jump to navigationJump to search
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
Extended instructions
- 1 M MgCl2 stock: dissolve 20.33 g MgCl2 6H2O in 100 ml ddH2O (XXX), autoclave on liquid cycle @ XXX°C for 20 min (can be done at the same time as SOC pre-mix below)
- 250 mM KCl stock: dissolve 1.86 KCl in 100 ml ddH2O (XXX)
- combine:
Reagent | for 1 L | 500 mL | 100 mL |
---|---|---|---|
tryptone | 20 g | 10 g | 2g |
yeast | 5g | 2.5 g | 0.5 g |
NaCl | 0.5 g | 0.25 g | 0.05 g |
250 nM KCl | 10 mL | 5mL | 1 mL |
ddH2O | 980 ml | 490 ml | 98 ml |
- adjust pH to 7.0 w/ NaOH
- bring to volume:
Reagent | for 1 L | 500 mL | 100 mL |
---|
- autoclave on liquid cycle @ XXX°C for 20 min
- add autoclaved 1 M MgCl2
Reagent | for 1 L | 500 mL | 100 mL |
---|---|---|---|
1 M MgCl2 | 10 ml | 5 ml | 1 ml |
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.