Peptone: Hydrolyzed product of animal and plant proteins: Free amino acids, peptides and proteoses(large sized peptides). It provides nitrogen; as well carbohydrates, nucleic acid fractions, minerals and vitamins. Meat extract: supply amino acids, vitamins and mineral salts. Yeast extract: It is bacterial growth stimulants. Mineral salts: these are: Sulfates as a source of sulfur.
. Phosphates as a source of phosphorus. . Sodium chloride
. Other elements
Carbohydrates: Simple and complex sugars are a source of carbon and energy.
.Assist in the differentiation of bacteria. Eg. Sucrose in TCBS agar differentiates vibro species.
Lactose in MacConkey agar differentiates enterobacteria. Agar: It is an inert polysaccharide of seaweed. It is not metabolized by micro-organism. Property . It has . high gelling strength . high melting temperature(90-95 oc) . low gelling temperature . It forms firm gel at 1.5% W/V concentration. . It forms semisolid gel at 0.4-0.5% W/V concentration. Uses: . Solidify culture media