General media contain substantial nutrients and will support the growth of a wide variety of microorganisms. General media is used to support a variety of applications, including enumeration of bacterial cultures, isolation of pure bacterial cultures and culture storage. The effective culture medium must contain all the nutrients required for the growth of the microorganism. Examples of standard general purpose media that will support the growth of a wide variety of bacteria include nutrient broth or agar and trypticase soy broth (TSB) or trypticase soy broth agar (TSB). A medium may be enriched, i.e., by the addition of blood or serum. Examples include sheep blood agar and chocolate (heated blood) agar. Certain microorganisms have very specific growth requirements and require specific formulations.