Date of Award


Document Type

Doctoral Thesis

Degree Name

Doctor of Philosophy


Biological Sciences

First Advisor

Dr Olivia McAuliffe

Second Advisor

Dr Kieran Jordan

Third Advisor

Dr Aidan Coffey


The objective of this study was to investigate the genetic characteristics of Listeria monocytogenes that contribute to the threat it poses to the food processing industry. Transcriptomic analysis of a persistent L. monocytogenes isolate following exposure to an industrial detergent identified key upregulations in biological processes involved m peptidoglycan biosynthesis, chemotaxis and motility. Two bacteriophages against serotype 4b and 4e isolates of L. monocytogenes were isolated and sequenced. Comparative genomic and functional analysis identified the receptor binding proteins in each phage, whi]e transmission electron microscopy demonstrated a conserved baseplate architecture which also exists in other Gram­positive phages. Comparative genomics of four serotype 1 /2b isolates, including an isolate that caused a sub-clinical infection (DPC6895), identified specific genes that may be important for L. monocytogenes pathogenesis. Attenuated virulence in strain DPC6895 was attributed to a cwnulative loss of functionality rather than a single event, exemplified by notable absences of the Stress Survival Islet and Listeria Pathogenicity Island 3 from its genome. Finally, the true discriminatory power of whole genome sequence analysis was assessed on two pairs of geographically distant, yet closely related L. monocytogenes isolates, which identified key differences in their antibiotic resistances and virulence potentials.

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