Phenylalanine agar or famously known as PPA agar slant tests the ability of an organism to produce the enzyme - Deaminase.
Deaminase converts phenylalanine to phenyl pyruvic acid (PPA) by removing an amine group from phenylalanine. Hence the name PPA agar. Phenylalanine serves as the substrate for the enzyme.
This is a biochemical test which helps to differentiate organisms of Providencia group from other Enterobacteriaceae.
Post incubation, 10% ferric chloride is added in to the slant. If any phenylpyruvic acid has been produced, then it will react with ferric chloride to yield a light to deep green color. If the media remains straw colored or becomes yellow then it is a negative result.
Positive results should be recorded in less than five minutes as the green color fades away after a while.
Positive result - Proteus mirabilis, Proteus vulgaris.
Negative results - E.coli, B.subtilis.
Hope it helps you all :)
Never forget to be amazing <3
-Staph
Deaminase converts phenylalanine to phenyl pyruvic acid (PPA) by removing an amine group from phenylalanine. Hence the name PPA agar. Phenylalanine serves as the substrate for the enzyme.
This is a biochemical test which helps to differentiate organisms of Providencia group from other Enterobacteriaceae.
Post incubation, 10% ferric chloride is added in to the slant. If any phenylpyruvic acid has been produced, then it will react with ferric chloride to yield a light to deep green color. If the media remains straw colored or becomes yellow then it is a negative result.
Positive results should be recorded in less than five minutes as the green color fades away after a while.
Positive result - Proteus mirabilis, Proteus vulgaris.
Negative results - E.coli, B.subtilis.
Hope it helps you all :)
Never forget to be amazing <3
-Staph
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