Physiological differentiation in swarming salmonella

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dc.contributor.advisorSurette, Michael G.
dc.contributor.authorKim, Wook
dc.date.accessioned2005-08-16T17:06:17Z
dc.date.available2005-08-16T17:06:17Z
dc.date.issued2004
dc.descriptionBibliography: p. 267-287en
dc.description.abstractSwarming behaviour in bacteria has been traditionally described as a surface motility phenotype observed on laboratory media. Swarming motility is a collective behaviour of groups of bacterial cells, and unlike the classic swimming motility in broth, vegetative cells must first differentiate into elongated and hyperflagellated swarmer cells. The extent of the morphological changes associated with swarmer differentiation can vary significantly between different organisms. Recent studies indicate that swarmer differentiation represents much more than a motility phenotype, as several clinically important attributes are co-regulated with swarming. In this work, I demonstrate that swarmer differentiation in Salmonella enterica serovar Typhimurium is coupled to elevated resistance to a wide variety of structurally and functionally distinct classes of antibiotics. One mechanism of resistance was directly attributed to the up-regulation of the pmrHFIJKLM operon, and evidence was presented that other mechanisms are likely associated. Adaptive antibiotic resistance in the absence of overt selection suggests that swarmer differentiation may reflect the organism's adaptation to the host environment; not due to antibiotic use, but to the role of host-derived cationic peptides and resident microflora-derived colicins and toxic metabolites that shape the intestinal ecosystem. Proteomic analyses revealed that migrating swarmer cells are metabolically differentiated compared to the vegetative swimmer cells grown in the same nutrient environment. Furthermore, once the cells have differentiated, the swarmers remain in this physiological state under conditions that do not promote the initial differentiation. The permeability of the swarmers' outer membrane was predicted to be relatively reduced, which in part accounts for the multiple antibiotic resistance phenotype. Moreover, the bacterium's capacity to override some of the classic paradigms of metabolic regulation, established in aqueous environments, represents a unique physiological response by the pathogen that may be advantageous in polymicrobial environments such as the host. In addition, cellĀ­cell signalling systems were differentially regulated, suggesting that the differentiated cells are also primed to respond to the presence of other organisms and its own increasing population. An experimental model system was developed to measure spatiotemporal gene expression patterns to study gene regulation in the context of transitions between cellular states.en
dc.format.extentxiv, 287 leaves : ill. ; 30 cm.en
dc.identifier.citationKim, W. (2004). Physiological differentiation in swarming salmonella (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/18591en_US
dc.identifier.doihttp://dx.doi.org/10.11575/PRISM/18591
dc.identifier.isbn0494046015en
dc.identifier.lccAC1 .T484 2004 K445en
dc.identifier.urihttp://hdl.handle.net/1880/41668
dc.language.isoeng
dc.publisher.institutionUniversity of Calgaryen
dc.publisher.placeCalgaryen
dc.rightsUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
dc.titlePhysiological differentiation in swarming salmonella
dc.typedoctoral thesis
thesis.degree.disciplineMicrobiology & Infectious Diseases
thesis.degree.grantorUniversity of Calgary
thesis.degree.nameDoctor of Philosophy (PhD)
ucalgary.item.requestcopytrue
ucalgary.thesis.accessionTheses Collection 58.002:Box 1511 520492028
ucalgary.thesis.notesUARCen
ucalgary.thesis.uarcreleaseyen
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