Final answer:
The reagent used in the Phenylalanine Deaminase Test is ferric chloride (FeCl3), which reacts with phenylpyruvic acid to produce a green compound, indicating the enzyme activity.
Step-by-step explanation:
The reagent used in the Phenylalanine Deaminase Test is ferric chloride (FeCl3). The test is a biochemical assay used to determine the ability of an organism to produce the enzyme phenylalanine deaminase, which catalyzes the removal of the amino group from phenylalanine, resulting in the production of phenylpyruvic acid. Ferric chloride is then added to the medium, and if phenylpyruvic acid is present, it will react with the ferric chloride to produce a green compound, indicating a positive result for the presence of phenylalanine deaminase activity.