Listeria monocytogenes is a human foodborne pathogen capable of causing invasive and non-invasive infections. Ubiquitous in the environment, strains are often classified into lineages I (serovars 1/2a, 1/2c, 3a; food); II (containing serovars 1/2b, 4b, 3b; human illness); and III (4a, 4c; food-production). It is not clearly understood how serovars become tropic to a particular niche. The objective of this project was to investigate strain differences in clinical, environmental and food isolates, with the aim of identifying genomic features responsible for the tropism of the microorganism for clinical, food and environmental niches.
Comparative genomic techniques, namely mixed-genome microarrays, dot-blot hybridization and suppressive subtractive hybridization were used to compare the genomes of L. monocytogenes isolates of different serotypes from a variety of different sources. Over 30 genome sequences, potentially involved in the tropism of the microorganism, were identified using Versions 2 and 3 of a Listeria mixed-genome array. These included genes with similarities to cystathionine beta-lyase and homoserine O-acetyltransferase, a putative outer-membrane lipoprotein, conserved hypothetical proteins, a peptidoglycan lytic protein and a glycosyltransferase family 65 enzyme.
The glycosyltransferase family 65 gene was found to be present in isolates belonging to lineage II but was absent in lineage I isolates. By creating an isogenic deletion mutant of this gene, it was found that this enzyme is involved in cell wall biosynthesis and could be responsible for increased survival of lineage II strains in the host environment, thus rendering these isolates more prevalent in cases of human listeriosis.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/27710 |
| Date | January 2008 |
| Creators | McIlwham, Sarah C |
| Publisher | University of Ottawa (Canada) |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 162 p. |
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