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Title: Effect of food storage conditions on the survival of Campylobacter jejuni
Author: Thomas, Richard James
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2001
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Campylobacter jejuni is the predominant cause of gastro-enteritis in the developed world, accounting for 58, 000 diagnosed cases in the U.K in 1998. Infection primarily results from consumption of undercooked poultry and poor preparatory hygiene. C. jejuni is a poultry commensal, hence products are frequently contaminated within the processing plant, and subsequently at retail. Survival under conditions imposed by poultry processing and storage is an important factor in the capability of C. jejuni to produce infection. C. jejuni cells are usually spiral, but can be converted to a spherical form (coccoid) under various conditions. A triphasic survival curve is exhibited upon exposure to cold-shock (4-20 °C), consisting of plateau, decline and non-plateable phases. Maximum survival was observed for stationary phase cells incubated at 4 °C under a microaerobic atmosphere. Loss of plating ability on Brucella-FBP medium occurred before coccoid transformation at all temperatures examined (37, 20 and 4 °C) indicating the formation of a non-plateable spiral state. Entry into the non-plateable state correlated with an increase in calcofluor white (CFW) staining. When the population of CFW-stained cells was below 80-90%, the cells could be resuscitated from the non-plateable state upon temperature upshift and dilution into fresh Brucella-FBP broth. An inhibitory factor was present in the spent medium preventing resuscitation. Further entry into the non-plateable state resulted in loss of cytoplasmic integrity. The maximum 'window of resuscitation' was 3.5 d under a microaerobic atmosphere at 4 °C. Cells incubated microaerobically, or at higher temperatures (20 °C), had a reduced window of resuscitation. Unlike Escherichia coli and Salmonella typhimurium, C. jejuni does not produce any cold-shock specific proteins as part of an adaptive stress response, at either 32, 25 or 4 °C, as indicated by 2D-PAGE analysis. These results were confirmed by analysing the newly sequenced genome for cold-shock protein homologues. Adaptive stress responses reliant on de novo protein synthesis were observed for hydrogen peroxide and trisodium phosphate via analysis of unstressed and stressed 2D-PAGE profiles.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available