Lysine Iron Agar

Lysine Iron Agar is used for the differentiation of microorganisms on the basis of lysine decarboxylase and hydrogen sulfide production in a laboratory setting. Lysine Iron Agar is not intended for use in the diagnosis of disease or other conditions in humans.

Lysine Iron Agar is prepared according to the formulation of Edwards and Fife, who developed the medium to detect Salmonella arizonaeS. arizonae ferments lactose rapidly, and the authors found expected H2S production on Triple Sugar Iron Agar was suppressed. By eliminating lactose and incorporating lysine, Edwards and Fife devised a medium differentiating enteric bacilli based on their ability to decarboxylate or deaminate lysine and produce abundant hydrogen sulfide. This medium is recommended for detecting rapid lactose-fermenting S. arizonae.

Lysine Iron Agar is specified in standard methods for Salmonella testing.


Formula Liter
Enzymatic Digest of Gelatin 5 g
Yeast Extract 3 g
Dextrose 1 g
L-Lysine 10 g
Ferric Ammonium Citrate 0.5 g
Sodium Thiosulfate 0.04 g
Bromcresol Purple 0.02 g
Agar *13.5 g

*10 – 15 g according to gel strength
Final pH: 6.7 ± 0.2 at 25°C
Formula may be adjusted and/or supplemented as required to meet performance specifications.


  1. Suspend 33 g of the medium in one liter of purified water.
  2. Heat with frequent agitation and boil for one minute to completely dissolve the medium.
  3. Dispense into test tubes and autoclave at 121°C for 15 minutes.
  4. After autoclaving, allow medium to solidify in a slanted position.

Order Details

Product # Product Description
7211A Lysine Iron Agar, 500 g
7211T Lysine Iron Agar, 5 kg