SOB medium

SOB (Super Optimal Broth) is a complex nutrient medium that is mainly used to produce and transform competent bacteria. The composition was formulated in 1983 by Douglas Hanahan .

composition

SOB is a complex medium with the following ingredients:

• Yeast extract 0.5% (w / v) (5 g / l)
• Tryptone 2% (w / v) (20 g / l)
• Sodium chloride 10 mM (0.6 g / l)
• Potassium chloride 2.5 mM (0.2 g / l)
• Magnesium chloride 10 mM
• Magnesium sulfate 10 mM

The medium is prepared without Mg ²⁺ and autoclaved at 121 ° C for 20 min . Before use, 20 mM Mg ^{2+ is} added to the nutrient medium (20 ml / l of a 1 M Mg ²⁺ solution which was prepared by mixing equal volumes of 1 M MgCl ₂  · 6H ₂ O and 1 M MgSO ₄  · 7H ₂ O) ). The pH is 6.8 to 7.

SOC consists of SOB to which 20 mM glucose has been added. It is particularly used in the transformation of bacteria.

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1. ↑ D. Hanahan (1983): Studies on transformation of Escherichia coli with plasmids . In: J. Mol. Biol. Vol. 166, No. 4, pp. 557-580, PMID 6345791