Deoxycholate Agar medium is used for the isolation and differentiation of Gram-negative enteric bacilli. Peptone is the nitrogen and vitamin source. Lactose is the main carbohydrate. Its fermentation releases acids, which produce a color shift in the pH indicator Phenol Red from red to yellow. Sodium Chlorate Dipotassium Phosphate maintain the pH and osmotic balance. Sodium Deoxycholate, Ferric Ammonium Citrate, and Sodium Citrate inhibit the growth of Gram-positive bacteria. Agar is the gelifying agent.