SOC Medium, shorthand for Super Optimal broth with Catabolite repression, is a nutritionally rich bacterial culture medium. The recipe is differs slightly with LB broth, containing 20 g/L tryptone, 5 g/L yeast extract, and 0.5 g/L sodium chloride. A defining ingredient is 20 mM glucose, which must be added separately after the media has cooled. SOC medium is typically used to grow competent cells to maximize the efficiency of bacterial plasmid transformations.