The impact of diet, gut microbiota and environmental factors on growth and pathogenicity of Listeria monocytogenes

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dc.check.date2027-05-31
dc.contributor.advisorGahan, Cormac G.
dc.contributor.authorCazzaniga, Monicaen
dc.contributor.funderHorizon 2020
dc.date.accessioned2026-01-23T12:38:08Z
dc.date.available2026-01-23T12:38:08Z
dc.date.issued2025
dc.date.submitted2025
dc.description.abstractThis thesis explores how diet, gut microbiota, and host immunity interact to influence Listeria monocytogenes infection. L. monocytogenes causes listeriosis, a serious foodborne disease increasingly linked to ready-to-eat foods. While its survival in food environments is well studied, its behaviour in the gastrointestinal tract and interactions with the microbiota remain less understood. Focusing on dietary polysaccharides chitin and chitosan, we investigated their effects on Listeria virulence and host–microbiota dynamics using in vitro, in vivo, and ex vivo models. Chitin and chitosan downregulated the virulence gene hlyA and reduced bacterial adhesion and invasion, likely via the VirSR regulatory system. In mice, chitosan improved microbiota composition and metabolic outcomes under a high-fat diet but did not prevent systemic infection. Conversely, chitin reduced bacterial burden and enhanced early immune activation, suggesting dual actions on pathogen virulence and host defences. Microbiota composition strongly influenced infection outcomes: experiments in SPF and Oligo-MM12 mice, supported by ex vivo fermentation, highlighted that host factors are essential for microbiota–pathogen interactions. Unexpectedly, certain Listeria strains displayed dendritic motility at 37°C under specific nutrient conditions, revealing a novel, strain-dependent motility phenotype linked to quorum sensing. Overall, this work shows that L. monocytogenes is highly responsive to dietary, environmental and microbial cues. These findings emphasize the potential of microbiota-informed dietary strategies for preventing foodborne infections and improving gut health.en
dc.description.statusNot peer revieweden
dc.description.versionAccepted Versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.citationCazzaniga, M. 2025. The impact of diet, gut microbiota and environmental factors on growth and pathogenicity of Listeria monocytogenes. PhD Thesis, University College Cork.
dc.identifier.endpage414
dc.identifier.urihttps://hdl.handle.net/10468/18445
dc.language.isoenen
dc.publisherUniversity College Corken
dc.relation.projectinfo:eu-repo/grantAgreement/EC/H2020::MSCA-ITN-ETN/956279/EU/Colonization resistance: training and research towards microbiome derived solutions to foodborne disease/COL_RES
dc.rights© 2025, Monica Cazzaniga.
dc.rights.urihttps://creativecommons.org/licenses/by-nc-nd/4.0/
dc.subjectListeria monocytogenes
dc.subjectPathogenicity
dc.subjectEnvironmental factors
dc.subjectDietary compounds
dc.subjectGut microbiome
dc.subjectHost responses
dc.subjectImmune responses
dc.titleThe impact of diet, gut microbiota and environmental factors on growth and pathogenicity of Listeria monocytogenes
dc.typeDoctoral thesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD - Doctor of Philosophyen
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