A recent study conducted by a research group at the University of Michigan* demonstrated the prevalence of Listeria monocytogenes both on apples and the environment of the packing plant.  Among three fruit packing facilities sampled, one had significantly high levels of Listeria monocytogenes.

In evaluating the reasons for the differences among packing plants, the scientist determined that biofilms on food contacts surfaces promoted the proliferation and persistence of Listeria. Research demonstrated that Pseudomonas spp. are responsible for biofilms that protect Listeria from decontamination. The knowledge gained from the investigation will be applied to developing more effective methods to reduce Listeria contamination in food packing plants.

The findings will also be of value for plants producing other foods including cold cuts and in relation to recent events, hard-cooked peeled eggs.

*Tan, X. et al. The occurrence of Listeria monocytogenes is associated with built environment microbiota in three tree-fruit processing facilities.  Microbiome. 7: article 115 [2019]