Endo agar



Endo agar (also called Endo's medium) is a microbiological growth medium with a faint pink colour. Originally developed for the isolation of Salmonella typhi, it is now used mostly as a coliform medium. Most gram-negative organisms grow well in this medium, while growth of gram-positive organisms is inhibited. Coliform organisms ferment the lactose in this medium, producing a green metallic sheen (i.e. Escherichia coli), whereas non-lactose-fermenting organisms produce clear, colourless colonies, i.e. Salmonella species.

Typical composition
Endo agar typically contains (w/v):
 * 1.0 % peptone
 * 0.25 % dipotassium hydrogen phosphate (K2HPO4)
 * 1.0 % lactose
 * 0.33 % anhydrous sodium sulfite (Na2SO3)
 * 0.03 % fuchsine
 * 1.25 % agar