Understanding Stress Adaptation during the Transition of Listeria monocytogenes from Environment to Food to Host

Listeria monocytogenes is widely distributed in the environment and a rare, though serious, cause of foodborne disease. The pathogen has the capacity to undergo molecular adaptation to very diverse environmental conditions as it enters the food-chain and ultimately the human host. We have used a number of approaches to determine how L. monocytogenes may adapt to stressful conditions (such as elevated osmolarity, low pH, low iron) encountered during growth in foods and transition to the host. These include whole-genome analyses, generation of gene knock-outs, transcriptional analysis and bioluminescence engineering (to track L. monocytogenes in complex environments). We note that the pathogen utilises shared systems to adapt to similar conditions encountered throughout the infectious cycle. The contribution of specific molecular systems to the survival of the pathogen in the food production environment, the food matrix and the host gastrointestinal tract will be discussed.