Abstract
The human pathogen L. monocytogenes and the animal pathogen L. ivanovii, together with four other species isolated from symptom-free animals, form the “Listeria sensu stricto” clade. The members of the second clade, “Listeria sensu lato”, are believed to be solely environmental bacteria without the ability to colonize mammalian hosts. To identify novel determinants that contribute to infection by L. monocytogenes, the causative agent of the foodborne disease listeriosis, we performed a genome comparison of the two clades and found 151 candidate genes that are conserved in the Listeria sensu stricto species. Two factors were investigated further in vitro and in vivo. A mutant lacking an ATP-binding cassette transporter exhibited defective adhesion and invasion of human Caco-2 cells. Using a mouse model of foodborne L. monocytogenes infection, a reduced number of the mutant strain compared to the parental strain was observed in the small intestine and the liver. Another mutant with a defective 1,2-propanediol degradation pathway showed reduced persistence in the stool of infected mice, suggesting a role of 1,2-propanediol as a carbon and energy source of listeriae during infection. These findings reveal the relevance of novel factors for the colonization process of L. monocytogenes.
Highlights
Listeria monocytogenes is a Gram-positive, facultative anaerobic, non-sporulating, rod-shaped bacterium[1]
To analyze the proliferation of different species from the Listeria sensu stricto and Listeria sensu lato groups in the gastrointestinal tract and in other organs, female BALB/c mice were orally infected with 4–9 × 108 cell forming units of the Listeria sensu stricto species L. monocytogenes and L. welshimeri, as well as the Listeria sensu lato species L. aquatica and L. booriae
We examined the transcription of lmo1131 and lmo1132 in L. monocytogenes EGDe at 24 °C and 37 °C under both aerobic and anaerobic growth conditions via quantitative real time-polymerase chain reaction (PCR) (Fig. 3)
Summary
Listeria monocytogenes is a Gram-positive, facultative anaerobic, non-sporulating, rod-shaped bacterium[1]. Together with L. marthii[21], L. innocua, L. welshimeri, and L. seeligeri, these two species form the “Listeria sensu stricto” group[22], one of two distinct clades in the genus Listeria All members of this clade (clade I) have been found in feces or the gastrointestinal tract of symptom-free animals, as well as in food of animal origin[23,24,25,26,27], suggesting a specific interaction of these species with mammalian hosts. A total of 151 gene products were identified as being encoded by all sensu stricto strains, but absent from the strains of the sensu lato group These factors that possibly contribute to the interaction of listeriae with mammals include the flagellum, the metabolic capabilities to utilize ethanolamine and 1,2-propanediol (1,2-PD), and a set of mainly functionally unknown proteins involved in regulation and transport processes. A putative transporter and the 1,2-PD degradation pathway were tested here for their function and their role during infection by L. monocytogenes
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call