Increased Adhesion of Listeria monocytogenes Strains to Abiotic Surfaces under Cold Stress

Abstract

Food contamination by Listeria monocytogenes remains a major concern for some food processing chains, particularly for ready-to-eat foods, including processed foods. Bacterial adhesion on both biotic and abiotic surfaces is a source of contamination by pathogens that have become more tolerant or even persistent in food processing environments, including in the presence of adverse conditions such as cold and dehydration. The most distinct challenge that bacteria confront upon entry into food processing environments is the sudden downshift in temperature, and the resulting phenotypic effects are of interest. Crystal violet staining and the BioFilm Ring Test® were applied to assess the adhesion and biofilm formation of 22 listerial strains from different serogroups and origins under cold-stressed and cold-adapted conditions. The physicochemical properties of the bacterial surface were studied using the microbial adhesion to solvent technique. Scanning electron microscopy was performed to visualize cell morphology and biofilm structure. The results showed that adhesion to stainless-steel and polystyrene was increased by cold stress, whereas cold-adapted cells remained primarily in planktonic form. Bacterial cell surfaces exhibited electron-donating properties regardless of incubation temperature and became more hydrophilic as temperature decreased from 37 to 4°C. Moreover, the adhesion of cells grown at 4°C correlated with affinity for ethyl acetate, indicating the role of cell surface properties in adhesion.

Bactericidal Activity of Usnic Acid-Chitosan Nanoparticles against Persister Cells of Biofilm-Forming Pathogenic Bacteria

“…The elongation and filamentation of L. monocytogenes is a unique finding in the present study. Numerous studies have reported the elongation and filamentation of L. monocytogenes cells in the presence of several environmental stress conditions such as temperature, salt, pH, and antimicrobials [76][77][78]. The elongation of L. monocytogenes cells by UA-CS NPs in the present study might be due to the inhibition of cell division.…”

Biofilms in the Food Industry: Health Aspects and Control Methods

“…Common contaminated foods are smoked fish, cold cuts and fresh cheese. Together with this low temperature replication ability, this bacterium enhances its hydrophilicity and induces biofilm status as a response to cold temperatures, increasing its attachment to surfaces and its resistance to cleaning procedures in many food factories ( Zhang et al, 2016 ; Lee et al, 2017 ). The eradication of this pathogen in the food industry is further complicated by its resistance to treatments up to 60°C ( Møretrø et al, 2017 ).…”

Listeria monocytogenes Virulence, Antimicrobial Resistance and Environmental Persistence: A Review

“…A biofilm is a population of bacterial cells attached to each other or a surface and enclosed by a self-produced matrix of extracellular polymeric substances (EPS) (proteins, polysaccharides, and extracellular DNA) [71]. The matrix is a nutrient reservoir, facilitates adhesion, acts as a protective barrier against heat and desiccation, heavy metals, ultraviolet rays, acids, and also inhibits the permeation of antimicrobial agents by restricting their diffusion potentials [72,73].…”