Growth, viability and architecture of biofilms of Listeria monocytogenes formed on abiotic surfaces

Abstract

The pathogenic bacterium Listeria monocytogenes can persist in food processing plants for many years, even when appropriate hygienic measures are in place, with potential for contaminating ready-to-eat products and, its ability to form biofilms on abiotic surfaces certainly contributes for the environmental persistence. In this research, L. monocytogenes was grown in biofilms up 8 days attached to stainless steel and glass surfaces, contributing for advancing the knowledge on architecture of mature biofilms, since many literature studies carried out on this topic considered only early stages of cell adhesion. In this study, biofilm populations of two strains of L. monocytogenes (serotypes 1/2a and 4b) on stainless steel coupons and glass were examined using regular fluorescence microscopy, confocal laser scanning microscopy and classic culture method. The biofilms formed were not very dense and microscopic observations revealed uneven biofilm structures, with presence of exopolymeric matrix surrounding single cells, small aggregates and microcolonies, in a honeycomb-like arrangement. Moreover, planktonic population of L. monocytogenes (present in broth media covering the abiotic surface) remained stable throughout the incubation time, which indicates an efficient dispersal mechanism, since the culture medium was replaced daily. In conclusion, even if these strains of L. monocytogenes were not able to form thick multilayer biofilms, it was noticeable their high persistence on abiotic surfaces, reinforcing the need to focus on measures to avoid biofilm formation, instead of trying to eradicate mature biofilms.

Evaluation of the Formation of Single- and Double-Species Biofilms on Intraventricular Catheters by Strains of Staphylococcus aureus, Listeria monocytogenes and Escherichia coli with K1 Antigen

“…In 2011 Le Monnier et al (25) described the case of a 3-year-old boy with ventriculoperitoneal shunt who had an infection with L. monocytogenes. This rod is able to form biofilms on many abiotic surfaces (26). Our study confirmed that IVCs may also be colonized by this microorganism.…”

Architecture and Viability of the Biofilms Formed by Nine Listeria Strains on Various Hydrophobic and Hydrophilic Materials

“…An intra-specific variability in biofilm architecture has also been reported by other authors. Among the different structures seen are one-cell-thick layers, flat layers of cells consisting of several layers without a given structure, honeycomb structures, and networks of interwoven clumps [35][36][37][38][39][40][41][42]. The great variability observed in the structure of the biofilms formed by Listeria spp.…”

Interaction and inactivation of Listeria and Lactobacillus cells in single and mixed species biofilms exposed to different disinfectants

“…de Oliveira et al () showed that L. monocytogenes quickly adhered to the surface and then the cells proliferated slowly. Reis‐Teixeira, Alves, and de Martinis () showed that L. monocytogenes formed not very dense biofilm with small aggregates and microcolonies, in a honeycomb‐like architecture on stainless steel and glass. It suggest that biofilms architecture can play an important role in biofilm resistance to antimicrobial agents.…”