FORMULA (g/L)
Tryptone 20.00
Sodium Chloride 0.50
Yeast Extract 5.00
Magnesium Chloride 0.96
Potassium Chloride 0.186
Final pH 7.0 ± 0.2 at 25ºC
PREPARATION
Suspend 26.6 grams of the medium in 1L of distilled water. Mix well and dissolve by heating with frequent
agitation. Boil for 1 minute until complete dissolution. Dispense into appropriate containers and sterilize at
121°C for 15 minutes. The prepared medium should be stored at 2-8°C. The color of the prepared medium is amber,
slightly opalescent.
The dehydrated medium should be homogeneous, free-flowing and beige in color. If there are any physical changes,
discard the medium.
USES
SOB MEDIUM is a nutrient rich medium for the preparation and transformation of competent cells. The transformation
requires perforation of the bacteria to allow the introduction of alien DNA. In order to survive this process
the competent cells need an isotonic rich medium.
Peptone provides nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is source of vitamins,
particularly the B-group. Sodium Chloride and Potassium Chloride supplies essential electrolytes for transport and osmotic
balance. Magnesium Sulfate is a source of magnesium ions.
Inoculate with the transformed cells and incubate at 35 ± 2°C for 18 - 24 hours.
MICROBIOLOGICAL TEST
The following results were obtained in the performance of the medium from cell cultures after incubation at 35 °C ± 2°C after 18 - 24 hours
Microorganism Growth
- Escherichia coli ATCC 23724 Good
- Escherichia coli ATCC 53868 Good
- Escherichia coli ATCC 33694 Good
- Escherichia coli ATCC 33849 Good