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Title: Techniques for the identification and differentiation of Cronobacter species
Author: Jackson, E. E.
ISNI:       0000 0004 6061 0820
Awarding Body: Nottingham Trent University
Current Institution: Nottingham Trent University
Date of Award: 2016
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The Cronobacter genus currently consists of seven species: C. condimenti, C. dublinensis, C. malonaticus, C. muytjensii, C. sakazakii, C. turicensis, and C. universalis. The work presented here was undertaken to examine different methods for detection, identification, and characterization of the members of this genus. First, traditional cultural, biochemical, and molecular detection and identification methods were examined with regard to taxonomic changes that occurred within the genus in 2013. This work showed that these methods may not be sufficient for accurate and specific detection and identification of all Cronobacter spp. Next, the DNA sequence-based method of multilocus sequence typing (MLST) was used to identify and characterize a collection of Cronobacter strains and these results were used in a variety of applications. These sequences were used to identify a novel species, characterize outbreak strains, and resolve discrepancies in species identification. It was also shown that MLST does not necessarily correlate to observable phenotypes. This led to the final portion of work which used whole genome sequences to guide laboratory experiments and data analysis. First, the mutS-rpoS genomic region of Cronobacter spp. was examined. Though this region is highly variable in other related species, all seven Cronobacter spp. contained the same genes in this region, in the same order, indicating that these genes are not likely to be related differences in virulence observed between the species. Finally, production of cellulose as a component of the bacterial capsule was examined. An attempt was made to link colony morphologies on infant formula agar and Congo red agar to the genotypes as determined from whole genome sequence analysis. While some results could be explained by the differences identified in the cellulose gene cluster, it was not possible to predict the phenotype based only on these gene sequences. This is likely due to the presence of four additional components in the capsule of Cronobacter spp. Future work developing a capsular typing scheme and linking these capsular profiles to observable phenotypes is also discussed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available