Lysine Decarboxylase Broth ISO 6579 Condalab 1176

Lysine Decarboxylase Medium is for the biochemical confirmation of Salmonella and Yersinia enterocolitica. This medium is recommended by ISO 6579 and ISO 19250 for the biochemical confirmation of Salmonella based on lysine decarboxylation. It is also recommended by ISO 10273 for the biochemical confirmation of Yersinia.

When the medium is inoculated with a bacterium that can ferment dextrose, the acid produced lowers the pH of the medium and changes colour on the indicator from purple to yellow. This acidic condition stimulates decarboxylase activity. The bacteria that decarboxylates the L-Lysine to cadaverine is identified by the presence of a purple-red colour. The production of these amines elevates the pH of the medium.

A yellow colour after 24 hours indicates a negative result, such as Yersinia. Yeast extract is the source of vitamins, of particularly the B-group, essential for growth. Dextrose is the fermentable carbohydrate. Bromocresol purple is the pH indicator. Lysine is added to detect the production of the specific enzyme.