High Concentrations of Benzalkonium Chloride Enhance Listeria monocytogenes Biofilm Formation

High Concentrations of Benzalkonium Chloride Enhance Listeria monocytogenes Biofilm Formation

Presenter(s)

Sydney Herzog

Comments

3:00-4:15, Kennedy Union Ballroom

Description

Listeria monocytogenes, a foodborne pathogen frequently detected in food processing environments, continues to cause product recalls and outbreaks despite strict cleaning protocols. Benzalkonium chloride (BAC), a widely used disinfectant, is effective against L. monocytogenes, but the ability of L. monocytogenes to form biofilms can reduce the efficacy of BAC by protecting the bacterial cells within the biofilm matrix. In this study, we used a standard microplate biofilm assay to investigate the impact of biofilms on L. monocytogenes susceptibility to BAC. Crystal violet staining revealed that exposure to higher BAC concentrations (≥0.1% [wt/vol]), either during or after biofilm formation, resulted in significantly increased biofilm levels regardless of different temperatures, surface types, and oxygen levels. This increase was not due to direct chemical interactions between crystal violet and BAC but required the presence of L. monocytogenes cells. Despite the observed biofilm augmentation, BAC inhibited both biofilm-associated metabolic activity as well as colony-forming units. Microscopic and survival assays suggested that the enhanced biofilm formation resulted from bacterial lysis, which led to cellular aggregation and greater surface adhesion. Overall, these findings indicate that elevated BAC concentrations, whether from direct application or environmental accumulation, can lead to the deposition of biofilm materials even in the absence of viable L. monocytogenes cells. This accumulation may facilitate the persistence of pathogens by promoting subsequent biofilm development by L. monocytogenes or other microbes. As a result, optimizing BAC concentrations and ensuring the removal of residual BAC are crucial for effective cleaning and disinfection strategies in food processing environments.

Publication Date

4-23-2025

Project Designation

Graduate Research

Primary Advisor

Yvonne Y. Sun

Primary Advisor's Department

Biology

Keywords

Stander Symposium, College of Arts and Sciences

Institutional Learning Goals

Scholarship; Practical Wisdom; Vocation

High Concentrations of Benzalkonium Chloride Enhance Listeria monocytogenes Biofilm Formation

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