Simple color tests based on an alanyl peptidase reaction which differentiate Listeria monocytogenes from other Listeria species.

The hydrolysis of DL-alanine-beta-naphthylamide and D-alanine-p-nitroanilide for identification of Listeria spp. has been studied with 227 cultures. All species of Listeria, except L. monocytogenes, hydrolyzed these substrates. The reactions were detected by simple chromogenic reactions and could substitute for the CAMP test.