title: Impact of environmental factors on the culturability and viability of Listeria monocytogenes under conditions encountered in food processing plants.
abstract: The ability of Listeria monocytogenes to adhere to and persist on surfaces for months or even years may be responsible for its transmission from contaminated surfaces to food products. Hence the necessity to find effective means to prevent the establishment of L. monocytogenes in food processing environments. The aim of this study was to assess, through a fractional experimental design, the environmental factors that could affect the survival of L. monocytogenes cells on surfaces to thereby prevent the persistence of this pathogen in conditions mimicking those encountered in food processing plants: culture with smoked salmon juice or meat exudate, use of two materials with different hygiene status, biofilm of L. monocytogenes in pure-culture or dual-culture with a Pseudomonas fluorescens strain, application of a drying step after cleaning and disinfection (C&D) and comparison of two strains of L. monocytogenes. Bacterial survival was assessed by culture, qPCR to quantify total cells, and propidium monoazide coupled with qPCR to quantify viable cells and highlight viable but non-culturable (VBNC) cells. Our results showed that failure to apply C&D causes cell persistence on surfaces. Moreover, the sanitation procedure leads only to a loss of culturability and appearance of VBNC populations. However, an additional daily drying step after C&D optimises the effectiveness of these procedures to reduce culturable populations. Our results reinforce the importance to use molecular tools to monitor viable pathogens in food processing plants to avoid underestimating the amounts of cells using only methods based on cell culture.
authors.affiliation: Université Paris-Est, Anses, Laboratory for Food Safety, 94701 Maisons-Alfort, France.
authors.forename: Anaïs
authors.initials: A
authors.lastname: Overney
authors.affiliation: Université Paris-Est, Anses, Laboratory for Food Safety, 94701 Maisons-Alfort, France.
authors.forename: Joséphine
authors.initials: J
authors.lastname: Jacques-André-Coquin
authors.affiliation: Université Paris-Est, Anses, Laboratory for Food Safety, 94701 Maisons-Alfort, France.
authors.forename: Patricia
authors.initials: P
authors.lastname: Ng
authors.affiliation: Université Paris-Est, Anses, Laboratory for Food Safety, 94701 Maisons-Alfort, France.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Carpentier
authors.affiliation: Université Paris-Est, Anses, Laboratory for Food Safety, 94701 Maisons-Alfort, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Guillier
authors.affiliation: Université Paris-Est, Anses, Laboratory for Food Safety, 94701 Maisons-Alfort, France. Electronic address: olivier.firmesse@anses.fr.
authors.forename: Olivier
authors.initials: O
authors.lastname: Firmesse
mesh_terms: D001422:Bacterial Adhesion; D018441:Biofilms / Q000254:growth & development*; D003890:Desiccation / Q000379:methods*; D004203:Disinfection / Q000379:methods*; D005506:Food Contamination / Q000517:prevention & control*; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D005525:Food-Processing Industry / Q000295:instrumentation; D008089:Listeria monocytogenes / Q000254:growth & development* / Q000502:physiology; D008460:Meat / Q000382:microbiology; D011551:Pseudomonas fluorescens / Q000254:growth & development* / Q000502:physiology
keywords: Cleaning & disinfection; Drying; Listeria monocytogenes; Persistence; Survival; Viable but non-culturable