Phenylalanine Agar

Differentiate enteric gram-negative bacilli (e.g., Morganella and Providencia^1,2) on the basis of deamination of phenylalanine using Thermo Scientific™ Remel™ Phenylalanine Agar. In 1950, Henriksen reported Proteus species were able to convert phenylalanine to phenylpyruvic acid³. Later, Buttiaux et al. described a method for detection of phenylpyruvic acid, formed as a result of phenylalanine deamination⁴. Bynae incorporated phenylalanine into an agar used to grow the organism^5,6. Ewing et al. modified the formulation of Bynae by omitting proteose peptone⁷.

The ability of an organism to oxidatively deaminate phenylalanine to phenylpyruvic acid is an important reaction in the differentiation of Enterobacteriaceae. This criterion is used to identify and differentiate enteric gram-negative bacilli from other members of Enterobacteriaceae which lack such an activity.

• Ready to use: Convenience of a prepared media
• Easy to interpret: A positive test is indicated by green color development within 1-5 minutes, whereas there is no color change in case of a negative test.
• Recommended by the Association of Official Analytical Chemists (AOAC)⁸.

The medium contains yeast extract that supplies B-complex vitamins and other nutrients to support the growth of bacteria. Sodium chloride provides essential electrolytes and maintains osmotic equilibrium. Phenylalanine acts as the substrate which undergoes oxidative deamination. This reaction is catalyzed by an amino acid oxidase enzyme and yields the alpha keto acid  phenylpyruvic acid. Ferric chloride (10%) added to Phenylalanine Agar after incubation serves as a chelating agent, which combines with phenylpyruvic acid to form a green color.

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