Techniques for the identification and differentiation of Cronobactor species

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Jackson, E.E., 2016. Techniques for the identification and differentiation of Cronobactor species. PhD, Nottingham Trent University.

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Abstract

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.

Item Type:	Thesis
Creators:	Jackson, E.E.
Date:	September 2016
Rights:	This work is the intellectual property of the author, Emily E. Jackson. You may copy up to 5% of this work for private study, or personal, non-commercial research. Any re-use of the information contained within this document should be fully referenced, quoting the author, title, university, degree level and pagination. Queries or requests for any other use, or if a more substantial copy is required, should be directed to the owner(s) of the Intellectual Property Rights.
Divisions:	Schools > School of Science and Technology
Record created by:	Linda Sullivan
Date Added:	07 Feb 2017 17:12
Last Modified:	08 Feb 2017 08:29
URI:	https://irep.ntu.ac.uk/id/eprint/30105