SOB Growth Medium

Principle and Interpretation

SOB Growth Medium is used for preparing competent cells prior to transformation. Super Optimal Broth (SOB medium) Growth Medium was first formulated by Douglas Hanahan in 1983 as a nutritionally enriched growth media for bacteria, especially Escherichia coli. It is used in the preparation and transformation of chemically competent cells. E. coli cells are first made competent during transformation where perforations are made in the bacterial cells so that the foreign DNA can penetrate the cells. To endure this process, competent cells require a rich isotonic medium. Tryptone provides nitrogen, amino acids and other growth factors which permit the cells to go through the stress of transformation. Vitamins and trace elements are contained in Yeast Extract. Sodium chloride provides essential ions for transport and osmotic balance. Magnesium sulfate provides magnesium ions which are required in a variety of enzymatic reactions, including DNA replication.