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Title: The effect of metal peroxides on the survival of campylobacter jejuni and the role of CorA in magnesium uptake
Author: Mohd Esah, Effarizah
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 2013
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The initial aim of this study was to investigate the potential of oxygen releasing compounds as an antimicrobial treatment to reduce the transmission of C. jejuni. C. jejuni was highly sensitive to Mg02 Ca02 and 2Na2CO3H202 when exposed to these compounds in Maximum Recovery Diluent (MRD), Ultra Heat Treated (UHT) skimmed milk and soil microcosms. in MRD, initial counts of 1 x 107 colony forming units per ml fell to undetectable levels in 32, 8 and 4 hours in the presence of 0.26, 2.6 and 5.2 mM Mg02 respectively. The same reduction in viability of C. jejuni was seen within 10 minutes and 30 minutes in the presence of 5.2 mM, 2.6 mM and CaO2 respectively. When C.jejuni cells were exposed to 2.6 mM -and 5.2 mM 2NazCO).31-hCh. viable counts fell by 7-logs in 15 minutes. The survival of C. jejuni when exposed to I-h02 was similar to that seen with Mg02 but when catalase was added, Mg02 had little impact on C. jejuni killing, suggesting that H20 2 formation via this metal peroxide is important in the killing process . Electron microscope observaltions revealed an irregular cell morphology and loss of cell wall integrity as well as loss of polar flagella. Cork (Cj0726C), the main magnesium transporter of C. jejuni, was inactivated by allelic exchange to determine whether magnesium transport was necessary for the oxidative killing seen with magnesium peroxide. The corA mutant did not grow without Mg2+ suppIementation (20 mM), indicating that Mg2+ acquisition by corA is essential for C.jeuni growth in vitro that might be important in adaptation to low-Mg2+ conditions. However, CorA was not essential in magnesium peroxide killing. Whilst a corA mutant showed a reduced ability to kill the larvae of Galleria mellonella, CorA did not appear to be required for chicken colonisation by oral gavage or for intracellular survival within Caco-2 cells
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available