Super optimal broth with catabolite repression, or SOC medium, is a bacterial growth medium used by microbiologists, explains Sigma-Aldrich. SOC is a nutrient-rich liquid broth that contains peptides, water-soluble vitamins and glucose. The medium is often used in the recovery step of competent cell transformations, especially for E. coli bacteria.
Standard super optimal broth, or SOB medium, contains the same components as SOC, except it contains no glucose. Carbon catabolite repression allows bacteria to adapt quickly to a preferred carbon and energy source and can be initiated by glucose. The exact components of SOC media are tryptone as a source for amino acids, yeast extract, dextrose, magnesium sulfate, sodium chloride and potassium chloride.