lmo0038 is involved in acid and heat stress responses and specific for Listeria monocytogenes lineages I and II, and Listeria ivanovii.

The genus Listeria comprises two pathogenic species, L. monocytogenes and L. ivanovii, as well as four nonpathogenic species, L. innocua, L. weishimeri, L. seeligeri, and L. grayi. Within L. monocytogenes, lineages I and II are responsible for most listeriosis cases, while lineage III strains are rarely associated with human morbidity but providing important clues for Listeria evolution. The gene lmo0038, belonging to the peptidylarginine deiminase family, was involved in the optimal growth under stress conditions, including low pH and heat shock (52 degrees C), and virulence potential. Further, this gene was specific to L. monocytogenes lineages I and II and L. ivanovii with significant similarities at nucleotide and amino acid levels. A novel multiplex PCR, based on lmo0038 in combination with optimized iap migration profiles, was developed for simultaneous identification of Listeria species and discrimination of L. monocytogenes lineage III, with a detection limit down to 1.0-9.0 x 10(2) CFU/mL. This assay was evaluated by 119 suspected Listeria food-related isolates and corrected 4 and 5 misidentifications by Listeria selective agar plate screening and API system, respectively. Therefore, this one-step molecular assay provides a rapid, reliable, and inexpensive screening test to detect Listeria species-particularly, the pathogenic species in surveillance programs concerning food safety and foodborne disease cases.