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ARS Home » Northeast Area » Wyndmoor, Pennsylvania » Eastern Regional Research Center » Characterization and Interventions for Foodborne Pathogens » Research » Publications at this Location » Publication #401329

Research Project: Molecular Analysis of Foodborne Pathogen Responses to Stressors

Location: Characterization and Interventions for Foodborne Pathogens

Title: Evaluation of longer-term biofilm formation of Listeria monocytogenes strains influenced by media compositions

item Chen, Chinyi
item Nguyen, Ly Huong
item Ramiah, Annapoorani
item Paoli, George

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/3/2023
Publication Date: 7/16/2023
Citation: Chen, C., Nguyen, L.T., Ramiah, A., Paoli, G. 2023. Evaluation of longer-term biofilm formation of Listeria monocytogenes strains influenced by media compositions. Meeting Abstract. Poster #P1-61.

Interpretive Summary:

Technical Abstract: Introduction: Biofilm is a major reservoir of persistent contamination by Listeria monocytogenes (Lm). Biofilm formation is influenced by bacterial cell physiology and abiotic conditions such as temperature, nutrient composition, and surface properties. Purpose: Most studies on Lm biofilm were conducted in a 1- to 2-day timeframe. Here, we evaluated the effect of common growth media on 3- and 10-day biofilm formation by a wide selection of Lm isolates from clinical, food, and environmental sources. Methods: We tested 27 Lm strains from diverse sources in LB (1% NaCl), BHI, TSB, MH and 1/10x LB and BHI to evaluate biofilm formation (crystal violet binding) and cell concentration (enumerated on 6x6 drop plates) at 30' on Day 3 and 10 post-inoculation. Additionally, LB-no salt (LBNS) and BHI + 1% NaCl (BHIS) were tested to assess the influence of NaCl. Media pH and dissolved oxygen levels were determined using a microbioreactor. Experiments were repeated at least twice on different days. Results: Biofilm formation was strongly strain-dependent. Some media favored biofilm formation: >70% of strains formed at least moderate biofilm in LB, >50% formed moderate biofilm in BHIS. BHI, TSB, and LBNS were the worst media for biofilm formation. NaCl levels =1% favored biofilm formation. One-tenth-strength LB or BHI resulted in poor growth and poor biofilm formation. Poor biofilm formation in TSB might be explained by a more dramatic drop in media pH. Significance: Lm continues to persist in factories and outbreak strains from the same factory decades apart were shown to be conserved. TSB is commonly used for Lm biofilm assays but, in comparison to other media, poorly supports biofilm formation. This may have led to an underestimate of Lm strains’ ability to form biofilm in previous reports. Our findings should help improve future experimental design to evaluate Lm’s capability in biofilm formation.