Genetic Features of Resident Biofilms Determine Attachment of Listeria monocytogenes

Abstract

Planktonic Listeria monocytogenes cells in food-processing environments tend most frequently to adhere to solid surfaces. Under these conditions, they are likely to encounter resident biofilms rather than a raw solid surface. Although metabolic interactions between L. monocytogenes and resident microflora have been widely studied, little is known about the biofilm properties that influence the initial fixation of L. monocytogenes to the biofilm interface. To study these properties, we created a set of model resident Lactococcus lactis biofilms with various architectures, types of matrices, and individual cell surface properties. This was achieved using cell wall mutants that affect bacterial chain formation, exopolysaccharide (EPS) synthesis and surface hydrophobicity. The dynamics of the formation of these biofilm structures were analyzed in flow cell chambers using in situ time course confocal laser scanning microscopy imaging. All the L. lactis biofilms tested reduced the initial immobilization of L. monocytogenes compared to the glass substratum of the flow cell. Significant differences were seen in L. monocytogenes settlement as a function of the genetic background of resident lactococcal biofilm cells. In particular, biofilms of the L. lactis chain-forming mutant resulted in a marked increase in L. monocytogenes settlement, while biofilms of the EPS-secreting mutant efficiently prevented pathogen fixation. These results offer new insights into the role of resident biofilms in governing the settlement of pathogens on food chain surfaces and could be of relevance in the field of food safety controls.

comK Prophage Junction Fragments as Markers for Listeria monocytogenes Genotypes Unique to Individual Meat and Poultry Processing Plants and a Model for Rapid Niche-Specific Adaptation, Biofilm Formation, and Persistence

“…L. monocytogenes can adhere to abiotic surfaces such as stainless steel, glass, plastic, polymers, and rubber that are present in the food processing environment (44,102,107). These bacteria also adhere to biotic surfaces such as other microorganisms and plant and animal tissues (44). Strains of L. monocytogenes show specificity in forming biofilms.…”

“…Initial adherence is critical for biofilm formation and depends on the physiochemical properties of the environmental surfaces as well as the biofilm-forming potential of the bacterial cells (18,83,102). L. monocytogenes can adhere to abiotic surfaces such as stainless steel, glass, plastic, polymers, and rubber that are present in the food processing environment (44,102,107). These bacteria also adhere to biotic surfaces such as other microorganisms and plant and animal tissues (44).…”

The role of cell-surface interactions in bacterial initial adhesion and consequent biofilm formation on nanofiltration/reverse osmosis membranes

“…However, one could argue that the reduced adhesion properties of the mucoid strain could in part be attributed to the viscoelastic properties of the mucoid layer, susceptible to shear stress. In a similar study, Habimana et al [49] showed that a EPS-producing mutant strain of a Lactococcus lactis strain was found to be not only highly hydrophilic, but also unable to properly adhere on glass. It was suggested that the produced EPS substances masked the real physicochemical properties of the cell, but also was susceptible to shear stress causing a delayed early colonization and slow biofilm formation.…”

Differential Biofilm Formation and Chemical Disinfection Resistance of Sessile Cells of Listeria monocytogenes Strains under Monospecies and Dual-Species (with Salmonella enterica) Conditions

“…Evidently, bacterial pathogens, such as L. monocytogenes and S. enterica, can be entrapped in multispecies sessile communities formed on such surfaces. In addition, attachment and biofilm formation by these two species have been shown to be influenced by either the natural in situ presence of other species or just their metabolic by-products (8,10,11,24,26,27,29,32,33,37,38,39,46,58,77). For instance, the presence of Staphylococcus xylosus and Pseudomonas fragi affected the numbers of L. monocytogenes biofilm cells on stainless steel (51), while compounds present in Hafnia alvei cell-free culture supernatant inhibited the early stage of S. enterica serovar Enteritidis biofilm formation on the same material (10).…”