Description: SOB Broth is recommended for use in cultivation of recombinant strains of Escherichia coli. It is a nutritionally rich growth medium for use in the preparation and transformation of competent cells. The transformation requires perforation of the bacteria to allow the introduction of foreign DNA inside the cell. 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 a source of vitamins, particularly from the B-group. Sodium chloride and Potassium chloride supply 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.
Directions for use: Dissolve 26.6 g of the dehydrated medium in one liter of distilled water. Mix well. Heat with frequent agitation until complete dissolution. Dispense into appropriate containers and sterilize in autoclave 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.
Composition: NEW Formula
– Tryptone: 20 g/L
– Yeast Extract: 5 g/L
– Magnesium Sulfate: 0.96 g/L
– Sodium Chloride: 0.5 g/L
– Potassium Chloride: 0.186 g/L
– Final pH 7.0 ± 0.2 at 25 ºC
Microbial Test: The following results were obtained in the performance of the medium from type cultures after incubation at a temperature of 35 ± 2°C and observed after 18-24 hours:
Microorganisms Growth
Escherichia coli ATCC 23724 Good
Escherichia coli ATCC 53868 Good
Escherichia coli ATCC 33694 Good
Escherichia coli ATCC 33849 Good
Soluble in: water
Storage: Store at room temperature. Once opened, keep the powdered medium closed to avoid hydration.
