Listeria monocytogenes attachment, survival and internalisation into cantaloupe
Fresh produce outbreaks have been increasing over the years, with the largest and deadliest global outbreak to date being attributed to whole cantaloupe contaminated with L. monocytogenes. Although cut cantaloupe have mostly been implicated in outbreaks due to contamination occurring during preparation, contamination of whole cantaloupe is particularly of concern. The surface of cantaloupe provides an ideal environment for microbial attachment and could easily be introduced into the flesh upon cutting. However, a large possibility also exist that harmful pathogens have the ability to internalise, especially during the washing step during post-harvest processing. Once internalised the pathogen is protected from various environmental factors, have access to enough nutrients and moisture which could lead to the pathogen proliferating to high and dangerous levels. The behaviour of L. monocytogenes on the cantaloupe rind and possible internalisation as well as factors such as serotype, environmental conditions and gene expression facilitating its behaviour requires extensive research. Moreover, L. monocytogenes has been shown to enter the Viable but Non Culturable state, which is cause for concern as it could result in the pathogen being undetected while maintaining virulence.
The aim of this study will be to investigate the ability of L. monocytogenes strains to attach, survive and internalise into whole fruits such as cantaloupe with special emphasis on the impact of storage temperatures, the ability to enter a VBNC state on the rind and the genes involved facilitating its behaviour.