Sodium chloride affectsListeria monocytogenesadhesion to polystyrene and stainless steel by regulating flagella expression

Abstract

Aim: To study the adhesion capability of seven strains of Listeria monocytogenes to polystyrene and stainless steel surfaces after cultivation at various NaCl concentrations. Methods and Results: Determination of growth limits indicated that all seven strains were able to grow in up to 11% NaCl in rain heart infusion and 3 g l−1 yeast extract–glucose at 20°C, but no growth was detected at 15% NaCl. Adhesion of L. monocytogenes was estimated after 4‐h incubation at 20°C in 96‐well microtitre plates. Statistical results revealed no significant difference between adhesion to polystyrene and stainless steel although surface properties were different. Adhesion between 0% and 6% NaCl was not different, whereas adhesion at 11% NaCl was significantly lower. This discrepancy in adhesion was correlated with the down‐regulation of flagella at 11% NaCl. Conclusions: Only high salinity levels, close to nongrowth conditions, repressed the expression of flagella, and consequently, decreased the adhesion capability of L. monocytogenes. Significance and Impact of the Study: Adhesion of L. monocytogenes to inert surfaces depends on environmental conditions that affect flagellum expression. High salinity concentrations would delay biofilm formation.

PFGE characterisation and adhesion ability of Listeria monocytogenes isolates obtained from bovine carcasses and beef processing facilities

“…4). Interestingly, NaCl concentrations exceeding 5% have been reported to inhibit L. monocytogenes adhesion (Jensen, Larsen, Ingmer, Vogel, & Gram, 2007), even in those strains that are capable of multiplying in culture medium with up to 15% NaCl (Caly, Takilt, Lebret, & Tresse, 2009).…”

Surface adhesins and exopolymers of selected foodborne pathogens

“…Several transposon mutagenesis studies supported the finding that mutations in flagella synthesis affect biofilm formation (Chang et al, 2012;Kumar et al, 2009;Ouyang et al, 2012). In addition to temperature, pH and salinity were also shown to have an influence on flagella biosynthesis and, consequently, L. monocytogenes adhesion (Caly et al, 2009;Tresse et al, 2006Tresse et al, , 2009. However, the absence of flagella only delayed biofilm formation but did not affect the final levels of adherent bacteria observed after longer periods of time (Vatanyoopaisarn et al, 2000).…”

The Effects of Sodium Chloride on the Physiological Characteristics of Listeria monocytogenes

“…monocytogenes forms a biofilm on food contact surfaces such as stainless steel, plastic, and rubber in meat processing environments, and environmental factors may affect biofilm formation ( monocytogenes had lower bacterial adhesion at 11% sodium chloride compared to 0% and 6% sodium chloride because the expression of genes related to flagella formation was down-regulated in the presence of 11% sodium chloride. These results indicate that the effect of sodium chloride on biofilm formation also depends on its concentration (Caly et al, 2009).…”

“…The exposure of L. monocytogenes to high acidity and then osmotic stress increased its tolerance to acidity and osmolality through acid adaptation and osmo-adaptation, respectively (Faleiro et al, 2003). Sodium chloride (5%) also increases biofilm formation by L. monocytogenes because of the production of extracellular polymeric substances rather than the accumulation of biofilm-forming cells (Pan et al, 2010); however, the influence of sodium chloride on biofilm formation is concentrationdependent (Caly et al, 2009 Therefore, objective of this paper was to review the effect of sodium chloride on various physiological characteristics of L. monocytogenes that is found in RTE meat and dairy products.…”