Sierra College Department of Biological Sciences

Microbiology Diagnostic Tests: Amino Acid Decarboxylation (Lysine)

This test is used to determine if or not bacteria can decarboxylate (remove a carboxyl group from) the amino acid lysine. Note - the amino acid ornithine may also be used.

Tube Sets:

-----------------A --------------------------------------------B---------------

1. Which of these tube sets contains organisms that are capable of decarboxylating the amino acid lysine?

2. What is the function of the vaspar seal, i.e., why are these tubes sealed with vaspar?

3. What is the name of the pH indicator in this medium?

4. What are the end products of decarboxylation, and how are they indicated, i.e., what evidence of decarboxylation is visible in the positive tube set?

5. What is the function of the control tube, i.e., why is a control tube necessary?

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