This test is used to detect the enzymatic ability of an organism  to decarboxylase (hydrolyse) an amino acid to
form an amine. Hydrolysis of an amino acid results in an alkaline pH change leading to formation of pink color.  formation pink color.

v
Requirements:-

1.      Glucose non-fermenting
organisms

2.      Glucose fermenting organisms

3.      Decarboxylase broaths (lysine, arginine, ornithine)

4.      Sterile mineral oil

5 Suspensions of suspected organisms grown on 5% sheep blood agar (18-24 hours) in brain- heart infusion broth (BHIB).

v Procedure:-

A.    Glucose non-fermenting organisms

1.       Prepare a heavy suspension of the organisms in brain-heart infusion broth.

2.       Inoculate each of the three decarbxylase broths and one control broth  (without amino   acid).

3.       Add a 4 mm layer of sterile mineral oil in each tube.

4.       Incubate at 37° up to seven days.

5.       Observe color change.

  B.       Glucose fermenting organisms

1.       Inoculate each of the decarboxylase tubes with 1 drop of brain-heart infusion broth   culture.

2.       Add 4 mm layer of sterile mineral oil in each tube.

3.       Incubate at 37° up to seven days.

4.       Observe color change.