SOC Medium
Per liter: To 950 mL of deionized H2O, add:
| Tryptone | 20 g |
| Yeast extract | 5 g |
| NaCl | 0.5 g |
SOC medium is identical to SOB medium, except that it contains 20 mm glucose. To prepare SOB medium, combine the above ingredients and shake until the solutes have dissolved. Add 10 mL of a 250 mm solution of KCl. (This solution is made by dissolving 1.86 g of KCl in 100 mL of deionized H2O.) Adjust the pH of the medium to 7.0 with 5 n NaOH (∼0.2 mL). Adjust the volume of the solution to 1 L with deionized H2O. Sterilize by autoclaving for 20 min at 15 psi (1.05 kg/cm2) on liquid cycle. Just before use, add 5 mL of a sterile solution of 2 m MgCl2. (This solution is made by dissolving 19 g of MgCl2 in 90 mL of deionized H2O. Adjust the volume of the solution to 100 mL with deionized H2O and sterilize by autoclaving for 20 min at 15 psi [1.05 kg/cm2] on liquid cycle.)
After the SOB medium has been autoclaved, allow it to cool to 60°C or less. Add 20 mL of a sterile 1 m solution of glucose. (This solution is made by dissolving 18 g of glucose in 90 mL of deionized H2O. After the sugar has dissolved, adjust the volume of the solution to 100 mL with deionized H2O and sterilize by passing it through a 0.22-µm filter.)
