P-379 - Salmonella enterica adapts to plant host using physiological and genetical mechanisms

Salmonella enterica adapts very well to plants using them as alternative hosts. In plant environment, Salmonellachanges its physiology. We previously identified two adaptative mechanisms: the heterogeneous expression of flagellin, which diminished the potential PTI response of the host plant and the use of fumarate. Since fresh produce were linked to numerous outbreaks, the understanding of mechanisms underlining pathogens adaptation contributes greatly to food safety. In addition to physiological, also genetical aspects contribute to Salmonella’s adaptation. Mobile genetic elements (plasmids) are of the critical concerns, which emerged in recent years. Among the many serovars, S. enterica serovarInfantis ranks as the fourth most commonly linked to human infections. It may carry the megaplasmid pESI (Plasmid of Emerging Salmonella Infantis). This self-transferring mosaic plasmid enhances colonization in mammals and improves Salmonella environmental fitness. It does so by carrying genes conferring resistance to various antibiotics, heavy metals, and disinfectants. In our study, we assessed the role of pESI in adaptation to plant environment. Two strains were used: with and without pESI. In addition, we obtained novel transconjugant strains. All were assessed in persistence and competition assays in planta. The study revealed that, while pESI offers clear advantages for colonization in mammalian hosts, it acts as a burden for S. Infantis persistence in plant environments.