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Access Type
WSU Access
Date of Award
January 2024
Degree Type
Dissertation
Degree Name
Ph.D.
Department
Nutrition and Food Science
First Advisor
Yifan Zhang
Abstract
The study aimed to assess the effectiveness of essential oil silver nanoparticles (EOAgNPs) conjugates against L. monocytogenes biofilms and explore potential applications in food processing systems. The oils used for this study were cinnamon, oregano, clove, eucalyptus, and rosemary extracts. EOAgNPs were individually screened against L. monocytogens (ATCC 19115) using broth micro dilution. Cinnamon EOAgNPs showed the highest antimicrobial efficacy against the test organism, as determined by the minimum inhibitory concentration (MIC). Oregano had the second-highest efficacy, while the other oils exhibited marginal antimicrobial activities. To determine the effect of the EOAgNPs on listeria biofilms, glass slide biofilm assays were performed. Results similar to the micro broth dilution method were observed, where cinnamon and oregano exhibited the highest cell death in the biofilm biomass. As the EOAgNPs presented promising use in controlling listeria biofilms, their potential toxicity was determined by preliminarily exposing them to brine shrimp. Followed by rat and human hepatic cell exposure in increasing concentrations, LDH assay was used to determine toxicity in cells. LC50 for all EOAgNPs was above four logs their respective concentrations. Finally, to assess the pathways the EOAgNPs might have affected a biosensor assay was conducted using V. harvyie, and a reduction in bioluminescence was observed, indicating interruption of autoinducer-mediated quorum sensing. To confirm these observations, qPCR analysis of agr A and agr C genes of the agr operon was performed, and up to a 12-fold reduction was observed. These results suggest that EOAgNPs have the potential to be used as antimicrobial agents to enhance food safety.
Recommended Citation
Tahlan, Varun, "Development Of Essential Oil-Based Silver Nanoparticle Conjugates And Their Effect On Listeria Monocytogenes Biofilms" (2024). Wayne State University Dissertations. 4145.
https://digitalcommons.wayne.edu/oa_dissertations/4145