Lab July 13 2009

Prepare SOB media and plates, http://openwetware.org/wiki/SOB.

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.

created 500 ml of SOB.

We used 1.5 g agar in 100 mL SOB for our plates.

autoclaved 400 ml SOB and 100ml SOB+agar and poured 5 plates.

obtained DH5α stocks from Crystal in Dr. Nano's lab.

using sterile technique and a sterile loop, scraped cells from DH5α seed culture, then streaked 4 plates. (1st 2 plates were still a bit warm, so were damaged.)

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