Lysine iron agar

Lysine iron agar or LIA is a differential media used to distinguish bacteria that are able to decarboxylate lysine and/or produce hydrogen sulfide from those that cannot.

[1] A liter of lysine iron agar contains 13.5g of the gelling agent agar, as well as the nutrients lysine (10 g), pancreatic digest of gelatin (5 g), yeast extract (3 g), glucose (1 g), ferric ammonium citrate (0.5 g), and sodium thiosulfate pentahydrate (40 mg).

Additionally, 20 mg of the indicator bromcresol purple is added.

Bacteria able to decarboxylate lysine will leave the media purple colored.

Here the LIA is solidified at an angle, then inoculated with bacteria by stabbing the agar to within 1/4 inch of the bottom of the tube and streaking the slant.