Lysine Decarboxylase Test
What is the purpose of the test?
The purpose is to see if the microbe can use the amino acid lysine as a source of carbon and energy for growth. Use of lysine is accomplished by the enzyme lysine decarboxylase.
How is lysine decarboxylase activity determined?
A medium containing lysine and a pH indicator is used. When lysine is used, the pH of the medium rises and the indicator changes color.
What medium is used?
The medium used is lysine decarboxylase broth. The medium is a nutrient broth to which 0.5% lysine is added. An important component of the medium is a modest amount of glucose, necessary for the process to proceed. The pH indicator brom cresol purple is purple at neutral or alkaline/basic pH but turns yellow at pH