Effects of propionate on Listeria monocytogenes fitness and pathogenesis in cold temperatures

Effects of propionate on Listeria monocytogenes fitness and pathogenesis in cold temperatures

    Presenter(s)

    Jadyn Nirschl

    Comments

    3:00-4:15, Kennedy Union Ballroom

    Description

    Listeria monocytogenes is a foodborne bacterium that has been repeatedly shown to have the ability to grow and survive under cold conditions, potentially increasing the risk of food contamination. To prevent food spoilage during cold storage, antimicrobial agents, such as propionate, are frequently added to inhibit microbial growth. As a result, L. monocytogenes could be exposed to propionate at refrigeration temperatures. However, how propionate affects L. monocytogenes fitness under cold conditions and subsequent infection is not currently known. In this study, we investigated the effects of cold propionate exposure on L. monocytogenes susceptibility to nisin (a common food additive) and lysozyme (a host degradative enzyme) as well as pathogenesis through listeriolysin O production and intracellular infections in RAW264.7 macrophages. In general, optical density of L. monocytogenes cultures did not decrease over a 7-day period incubation in the cold. However, the presence of propionate (25 mM) resulted in a significant decrease in OD after 7 days in the cold. Moreover, cold exposure altered L. monocytogenes cell morphology and increased susceptibility to nisin without changing susceptibility to lysozyme. While the presence of propionate did not affect LLO production during cold storage, cold pretreatment significantly increased bacterial entry into the macrophages. In summary, both cold temperature and propionate seem to influence L. monocytogenes fitness and pathogenesis to varying degrees, highlighting the need to better understand synergistic activities between cold temperatures and food additives. Additional work is needed to further elucidate mechanisms underlying the observed responses and provides recommendations for food safety.

    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; Critical Evaluation of Our Times

    Effects of propionate on Listeria monocytogenes fitness and pathogenesis in cold temperatures

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