PhD defence

Listeria monocytogenes stress resistant variants – Impact on high hydrostatic pressure processing efficacy

PhD candidate Ineke van Boeijen
Promotor prof.dr. T (Tjakko) Abee MH (Marcel) Zwietering
External copromotor Dr H.R. Moezelaar
Organisation Wageningen University, Food Microbiology Laboratory

Tue 28 March 2023 16:00 to 17:30

Venue Omnia
Room Auditorium


High hydrostatic pressure (HHP) is a minimal processing food technology used to inactivate spoilage and hazardous microorganisms. It was developed to fulfill consumer demand for safe and healthy food products with better texture and flavor.

An important hazardous microorganism requiring inactivation, is Listeria monocytogenes. This foodborne pathogen can cause listeriosis, a rare but severe disease that can be fatal to e.g. unborn babies and elderly people.

HHP inactivation of L. monocytogenes showed that part of the population survived the treatment. Further characterization of these survivors showed a large population diversity. Some of these survivors have mutations in a specific regulator gene, explaining their HHP resistance. Similar mutants were also found after pasteurization by heat. These new findings may be used to develop and implement processing technologies that can control this pathogen and reduce food safety risks.