Explain the Composition of MacConkey Agar?

Bactopeptone - 17.0 gm

Protease Peptone - 3.0 gm

Lactose - 10.0 gm

Bile salt mixture - 1.5 gm

Sodium chloride - 5.0 gm

Agar - 13.5 gm

Neutral Red - 0.03 gm

Crystal Violet - 0.001 gm

Distilled water - 1000 ml

pH - 7.1

MacConkey Agar is a specialized media used for selection and differentiation among different bacterial species. It contains crystal violet, which inhibits the growth of gram positive but permits gram negative to grow (selection).  Presence of lactose, bile salts and neutral red in medium allows differentiation of bacteria on basis of their ability to ferment lactose. This medium is used to differentiate members of Enterobacteriaceae, which are morphologically and biochemically related into 2 groups.