Cross-contamination of mature Listeria monocytogenes biofilms from stainless steel surfaces to chicken broth before and after the application of chlorinated alkaline and enzymatic detergents

Effects of Sub-Minimum Inhibitory Concentrations of Bacteriocin BM173 on Listeria Monocytogenes Biofilm Formation

Listeria monocytogenes is a significant foodborne pathogen that can form biofilms on various food processing surfaces, thereby enhancing resistance to disinfectants and exacerbating harm to human health. Previous studies have indicated that bacteriocin BM173 exhibits antibacterial and antibiofilm activities. In the current study, our aim was to assess the inhibitory mode of action of sub-inhibitory concentrations (SICs, 1/32 × MIC and 1/16 × MIC) of BM173 on the biofilm formation L. monocytogenes. Crystal violet staining assay revealed that SICs of BM173 significantly inhibit L. monocytogenes biofilm formation. Furthermore, the results of swimming motility assay, plate count, ruthenium red staining, and scanning electron microscopy (SEM) revealed that SICs of BM173 could effectively reduce the movement, cell adhesion, and exopolysaccharide (EPS) production of L. monocytogenes, thereby inhibiting biofilm formation. Real-time quantitative PCR analyses further demonstrated that SICs of BM173 down-regulated the expression of biofilm-associated genes, including those encoding adhesion, virulence factors, and quorum sensing. Additionally, SICs of BM173 effectively reduced the biofilm formation of L. monocytogenes on the surfaces of three food-grade materials (glass, stainless steel, and silicone) at 4 and 25 °C. These outcomes suggest that BM173 holds great potential for development as a promising food preservative for application in the food industry.

The promotion of biofilm dispersion: a new strategy for eliminating foodborne pathogens in the food industry

Food safety is a critical global concern due to its direct impact on human health and overall well-being. In the food processing environment, biofilm formation by foodborne pathogens poses a significant problem as it leads to persistent and high levels of food contamination, thereby compromising the quality and safety of food. Therefore, it is imperative to effectively remove biofilms from the food processing environment to ensure food safety. Unfortunately, conventional cleaning methods fall short of adequately removing biofilms, and they may even contribute to further contamination of both equipment and food. It is necessary to develop alternative approaches that can address this challenge in food industry. One promising strategy in tackling biofilm-related issues is biofilm dispersion, which represents the final step in biofilm development. Here, we discuss the biofilm dispersion mechanism of foodborne pathogens and elucidate how biofilm dispersion can be employed to control and mitigate biofilm-related problems. By shedding light on these aspects, we aim to provide valuable insights and solutions for effectively addressing biofilm contamination issues in food industry, thus enhancing food safety and ensuring the well-being of consumers.

The Relationship between Biofilm Phenotypes and Biofilm-Associated Genes in Food-Related Listeria monocytogenes Strains

Listeria monocytogenes is an important pathogen responsible for listeriosis, a serious foodborne illness associated with high mortality rates. Therefore, L. monocytogenes is considered a challenge for the food industry due to the ability of some strains to persist in food-associated environments. Biofilm production is presumed to contribute to increased L. monocytogenes resistance and persistence. The aims of this study were to (1) assess the biofilm formation of L. monocytogenes isolates from a meat processing facility and sheep farm previously characterized and subjected to whole-genome sequencing and (2) perform a comparative genomic analysis to compare the biofilm formation and the presence of a known set of biofilm-associated genes and related resistance or persistence markers. Among the 37 L. monocytogenes isolates of 15 sequence types and four serogroups involved in this study, 14%, 62%, and 24% resulted in the formation of weak, moderate, and strong biofilm, respectively. Increased biofilm-forming ability was associated with the presence of the stress survival islet 1 (SSI-1), inlL, and the truncated inlA genes. Combining the phenotypic and genotypic data may contribute to understanding the relationships between biofilm-associated genes and L. monocytogenes biofilm-forming ability, enabling improvement in the control of this foodborne pathogen.

Investigation of the Efficacy of a Listeria monocytogenes Biosensor Using Chicken Broth Samples

Foodborne pathogens are microbes present in food that cause serious illness when the contaminated food is consumed. Among these pathogens, Listeria monocytogenes is one of the most serious bacterial pathogens, and causes severe illness. The techniques currently used for L. monocytogenes detection are based on common molecular biology tools that are not easy to implement for field use in food production and distribution facilities. This work focuses on the efficacy of an electrochemical biosensor in detecting L. monocytogenes in chicken broth. The sensor is based on a nanostructured electrode modified with a bacteriophage as a bioreceptor which selectively detects L. monocytogenes using electrochemical impedance spectroscopy. The biosensing platform was able to reach a limit of detection of 55 CFU/mL in 1× PBS buffer and 10 CFU/mL in 1% diluted chicken broth. The biosensor demonstrated 83-98% recovery rates in buffer and 87-96% in chicken broth.

Recent advances on the formation, detection, resistance mechanism, and control technology of Listeria monocytogenes biofilm in food industry

Listeria monocytogenes is an important foodborne pathogen that causes listeriosis, a severe and fatal condition. Biofilms are communities of microorganisms nested within a self-secreted extracellular polymeric substance, and they protect L. monocytogenes from environmental stresses. Biofilms, once formed, can lead to the persistence of L. monocytogenes in processing equipment and are therefore considered to be a major concern for the food industry. This paper briefly introduces the recent advancements on biofilm formation characteristics and detection methods, and focuses on analysis of the mechanism of L. monocytogenes biofilm resistance; Moreover, this paper also summarizes and discusses the existing different techniques of L. monocytogenes biofilm control according to the physical, chemical, biological, and combined strategies, to provide a theoretical reference to aid the choice of effective control technology in the food industry.