Lysine Iron Agar 1044 Condalab

Lysine Iron Agar is used for the rapid differentiation of Enterobacteriaceae, especially Salmonella arizonae, based on lysine decarboxylation and deamination, and H2S production. This medium is very useful for the rapid differentiation of Salmonella arizonae from Citrobacter and Proteus spp. The strains that rapidly ferment the lactose produce a large quantity of acid, changing the original purple colour of the medium to yellow. Some strains of S. arizonae can rapidly ferment lactose and form colonies that are colourless or pink to red on media such as MacConkey Agar (Cat. CL-1052) or Desoxycholate Agar (Cat. CL-1020). Lysine Iron Agar is especially formulated to avoid this confusion.

Gelatin peptone and Yeast extract provide the nutrient sources for growth: nitrogen, vitamins, minerals, and amino acids. One reaction is the degradation of the fermentable carbohydrate Dextrose, with the production of acid, manifested in the colour change from red to yellow. Sodium thiosulfate provides Sulphur and Ferric ammonium citrate is the indicator for H2S production under alkaline conditions. The bacteria that decarboxylate the L-Lysine to cadaverine, such as Salmonella arizonae, are identified by the presence of a purple red colour due to the elevation of the pH. Bromocresol purple is the pH indicator and bacteriological agar is the solidifying agent.