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Competent Cells Medium Formulations

SOB is originally developed by Hanahan as a medium to prepare competent cells prior to transformation for maximizing transformation efficiency.  Transformation requires making perforations in the bacterium (i.e. making the cells ‘Competent’) to allow the introduction of foreign DNA into the cell.  To survive the process of perforating the cell, competent Escherichia Coli cells need a nutritionally rich and well balanced isotonic medium.

Tryptone and Yeast Extract are sources of nitrogen, vitamins, growth factors and carbohydrates supporting the cell to recover from the stress of transformation and subsequently grow well.

To set a well balanced isotonic environment Sodium Chloride and Potassium Chloride are present in the medium.

Magnesium ions required in a variety of enzymatic reactions including DNA replication are provided by Magnesium Sulfate.

SOC medium as used in the final stage of transformation and is prepared by adding glucose in a final concentration of 20 mM to SOB medium. The glucose added is a readily available carbon and energy source for Escherichia Coli cells in mending the perforations and for replication.

Hanahan, D., Studies on transformation of Escherichia coli with plasmids, J. Mol., Biol., 166, 557, 1983.
Sambrook, J,., E. F. Fritsch, and T. Maniatis, 1989, Molecular cloning: a laboratory manual, 2nd edition ed., Cold Spring Harbour laboratory, Cold Spring Harbour, N.Y.
Difco manual 11th ed., Sparks, MD (1998), 22-23.

  • SOB

    $23.74$89.74
    SKU Pack Size Price
    SOB0101 250g $23.74
    SOB0102 1000g $89.74
    Select options
    Formula
    g/l
    Tryptone 20
    Yeast extract 5
    NaCl 0.5
    MgSO4 2.44
    Final pH 7.0 ± 0.2 at 25°C
    Suspend 27.9 gram powdered medium in 1 litre distilled water Store dry at room temperature
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  • SOB, Hanahan’s Broth

    $23.74$89.74
    SKU Pack Size Price
    SOB0201 250g $23.74
    SOB0202 1000g $89.74
    Select options
    Formula
    g/l
    Tryptone 20
    Yeast extract 5
    NaCl 0.5
    MgSO4 2.44
    KCl 0.186
    Final pH 7.0 ± 0.2 at 25°C
    Suspend 28.1 gram powdered medium in 1 litre distilled water Store dry at room temperature
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  • SOA

    $26.16$98.41
    SKU Pack Size Price
    SOA0101 250g $26.16
    SOA0102 1000g $98.41
    Select options
    Formula
    g/l
    Tryptone 20
    Yeast extract 5
    NaCl 0.5
    MgSO4 2.44
    Agar 15
    Final pH 7.0 ± 0.2 at 25°C
    Suspend 42.9 gram powdered medium in 1 litre distilled water Store dry at room temperature
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  • SOA, Hanahan’s Agar

    $26.16$98.41
    SKU Pack Size Price
    SOA0201 250g $26.16
    SOA0202 1000g $98.41
    Select options
    Formula
    g/l
    Tryptone 20
    Yeast extract 5
    NaCl 0.5
    MgSO4 2.44
    KCl 0.186
    Agar 15
    Final pH 7.0 ± 0.2 at 25°C
    Suspend 43.1 gram powdered medium in 1 litre distilled water Store dry at room temperature
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  • SOC Agar

    $22.87$83.85
    SKU Pack Size Price
    SOC0101 250g $22.87
    SOC0102 1000g $83.85
    Select options
    Formula
    g/l
    Glucose 3.6 (20 mN)
    Tryptone 20
    Yeast extract 5
    NaCl 0.5
    MgSO4 2.44
    Agar 15
    Final pH 7.0 ± 0.2 at 25°C
    Suspend 46.5 gram powdered medium in 1 litre distilled water Store dry at room temperature
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  • SOC Broth

    $21.31$77.96
    SKU Pack Size Price
    SOC0202 1kg $77.96
    SOC0201 250g $21.31
    Select options
    Formula
    g/l
    Glucose 3.6 (20 mN)
    Tryptone 20
    Yeast extract 5
    NaCl 0.5
    MgSO4 2.44
    Final pH 7.0 ± 0.2 at 25°C
    Suspend 31.5 gram powdered medium in 1 litre distilled water Store dry at room temperature
    View product