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13 terms

Phenylalanine Deaminase Test

STUDY
PLAY
test involving catabolism of amino acids involves
amino acid phenylalanine
phenylalanine deaminase enzyme reaction is very useful to
differentiate members of the genera Proteus, Providencia, and Morganella (all positive) from the rest of the Enterobacteriaceae (all negative)
Organisms producing deaminase enzymes
remove an amino group (NH2) from phenylalanine to producephenylpyruvic acid and ammonia (NH3
Phenylpyruvic acid is detected by
adding acidified ferric chloride, an oxidizing agent, which reacts with the acid to produce a green color on the surface of the slant
green color is best viewed when looking at the
profile of the slant
organism lacks the deaminase enzyme
yellow color develops when acidified ferric chloride is added.
Proteus vulgaris (+) Escherichia coli (-)
Control bacteria
all positive
Proteus, Providencia, and Morganella
all negative
Enterobacteria
is phenylalanine an amino acid?
yes.
Organisms producing deaminase enzymes remove an amino group (NH2) from phenylalanine to produce
phenylpyruvic acid and ammonia (NH3)
how is Phenylpyruvic acid is detected
by adding acidified ferric chloride,which reacts with the acid to produce a green color on the surface of the slant.
ferric chloride
an oxidizing agent