How does m-Endo medium work?
Coliforms react with medium to produce dark red colonies with a greenish-gold sheen.
Coliforms ferment lactose in medium and produce an acid-aldehyde complex. This complex combines with Schiff's reagent (also in the medium) to form an iridescent green coating over the colonies. When magnified 10 to 15 times, coliforms appear as dark red colonies with a greenish-gold sheen.