Moeller Decarboxylase Broth w/ Lysine hydrochloride is supplied by HiMedia. It is a sterile ready prepared media containing 5ml of purple coloured solution in bottles. Moeller Decarboxylase Broth w/ Lysine Hydrochloride is generally used for differentiation of bacteria on the basis of their ability to decarboxylate L- Lysine hydrochloride. It is advisable to store this ready prepared media between 2-8C. Composition (in gm/L) is as follows:

Peptic digest of animal tissue (5.00)

Beef extract (5.00)

Dextrose (0.50)

Bromocresol purple (0.01)

Cresol red (0.005)

Pyridoxal ( 0.005)

L-Lysine hydrochloride (10.00)

This medium was formulated by Moeller for detecting the production of lysine and ornithine decarboxylase and arginine dihydrolase. Moeller Decarboxylase Broth with lysine hydrochloride is used for differentiating bacteria on their ability to decarboxylate lysine hydrochloride. This medium contains beef extract and peptic digest of animal tissue which provide nitrogenous nutrients for the growth of bacteria. Dextrose is the fermentable carbohydrate and pyridoxal is the co-factor for the decarboxylase enzyme. Bromo cresol purple and cresol red are the pH indicators in this medium. When the medium is inoculated with the dextrose fermenting bacteria, the pH is lowered due to acid production which changes the colour of the indicator from purple to yellow. Acid produced stimulates decarboxylase enzyme. Decarboxylation of lysine yields cadaverine. Formation of the amine cadaverine increases the pH of the medium, changing the colour of the indicator from yellow to purple. If the organisms do not produce the appropriate enzyme, the medium remains acidic, yellow in colour. Each isolate to be tested should also be inoculated into the basal medium tube lacking the amino acid. After incubation, a decarboxylase test may show two layers of different colours, yellow and purple.