ENDO agar

Specifications

Ingredients : gms/lit.
Peptone 10.00
Lactose 10.00
Dipotassium phosphate 3.50
Sodium sulphite 2.50
Basic fuchsin 0.50
Agar 15.00
Final pH (at 25°C) : 7.5 + 0.2

Instrustion for use :
Suspend 41.5 grams in 1000 ml distilled water. Heat to boiling to dissolve the medium
completely. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Mix well before
pouring into sterile Petri plates. If the solidified culture medium is somewhat too red, then to
remove the colour add a few drops (max. 1 ml/litre) of a freshly prepared 10% Sodium sulphite
solution and boil.

Principle :
The medium contains peptone which provide nitrogen, carbon, vitamins and minerals required for
bacterial growth. Sodium sulphite and basic fuchsin make this medium selective by suppressing
gram-positive organisms. Coliforms produce pink colonies on fermentation of lactose while lactose
non-fermenters produce colourless colonies on the medium. With Escherichia coli, this reaction is
very pronounced as the fuchsin crystallizes, exhibiting a permanent greenish metallic luster
(fuchsin luster) to the colonies.