Date of Award


Document Type

Master Thesis

Degree Name

Masters of Science (Research)


Cork Institute of Technology

First Advisor

Dr. Shea Fanning


Listeria monocytogenes is a gram-positive, food-borne human and animal pathogen. L.innocua is a non-pathogenic species the most closely related to L. monocytogenes. Comparative genomics between a pathogenic and a closely related non-pathogenic species is a powerful approach for identifying genes or regions on the chromosome, which might be involved in virulence. Therefore whole genome sequencing of these two organisms was undertaken. The strategy used was based on a random approach combined with end-sequencing of a medium insert library for the finishing phase. Based on the available sequence data for these two species an in silico analysis for the presence of genes putatively coding for internalins was undertaken. This analysis identified several genes homologous to the internalin coding sequences which are known virulence determinants of L. monocytogenes and also more than forty genes with an LPxTG anchor motif which is a feature of some cell wall associated proteins of gram positive organisms e.g. Internalins. Comparative in silico analysis of the two partially sequenced genomes revealed that certain of these genes are specific to the pathogenic L.monocytogenes and some to the non-pathogenic L.innocua. To investigate their distribution among the genus Listeria, amplification of these genes using the Polymerase Chain Reaction was carried out. This revealed a large degree of diversity within this protein family among the different species. Furthermore, three genes specific to L.monocytogenes, and two, specific to apathogenic species of Listeria were identified.

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