For differentiation of Proteus and Providencia group of organisms from other members of Enterobacteriaceae on the basis of their ability to form phenyl pyruvic acid from phenylalanine.
Phenyl Alanine Agar Slant is recommended for differentiation of Proteus and Providencia group of organisms from other members of Enterobacteriaceae on the basis of their ability to form phenyl pyruvic acid from phenylalanine. Positive reaction is indicated by development of light to deep green color on addition of 10% aqueous ferric chloride solution.