Nutrient agar is a general purpose medium that supports the growth of a wide range of non-fibrous organisms. Nutrient agar is popular because it supports the growth of various types of bacteria and fungi, and contains many of the nutrients necessary for the growth of bacteria. Nutrient agar can also be used for quality control and purity verification prior to biochemical or serological testing. Nutrient agar consists of peptone, beef extract and agar. It is a simple formulation but provides the nutrients necessary for the replication of a large number of microorganisms that are not too demanding. Beef extract contains water-soluble substances (carbohydrates, vitamins, nitrogen compounds and salts). Peptones are the main source of organic nitrogen, especially via amino acids and long-chain peptides. Agar is used as a gelling agent.