Himedia Lysine Iron Agar

Lysine Iron Agar is recommended for differentiation of enteric organisms especially Salmonella arizonae, based on their ability to decarboxylate or deaminate lysine and to form hydrogen sulphide (H₂S). Dextrose is a source of fermentable carbohydrate. Ferric ammonium citrate and sodium thiosulphate are indicators of H2S formation. Cultures that produce hydrogen sulphide cause blackening of the medium due to ferrous sulphide production. Lysine decarboxylation causes an alkaline reaction (purple colour) to give the amine cadaverine and the organisms which do not decarboxylate lysine, produce acid butt (yellow colour).