The lysine iron agar slant or LIA slant test is used to distinguish bacteria which are able to decarboxylate lysine and/or produce hydrogen sulfide from those that cannot. This test is particularly useful for distinguishing different Gram-negative bacilli—especially among the Enterobacteriaceae.
The LIA slant is inoculated by stabbing the agar to within 1/4 inch of the butt of the tube and streaking the slant. The slant is then incubated at 35°C for 18–24 hours. The results are scored as follows: