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Title: Studies on the respiratory system of Campylobacter mucosalis
Author: Goodhew, Celia Frances
ISNI:       0000 0001 3504 946X
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1988
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The microaerophilic, catalase-negative, gram-negative bacterium Campylobacter mucosalis was grown microaerobically with either hydrogen or formate as electron donor. A model is proposed for the respiratory adaptation of the organism to falling oxygen tensions during growth. During the early stages of growth, when the oxygen concentration is relatively high, the oxidation of formate is a two-stage branched process involving hydrogen peroxide production and its peroxidative removal. In later stages of growth, when the oxygen concentration is lower as a result of cellular respiration, the principal electron flow is linear to a membrane-bound cytochrome-c oxidase which reduces oxygen directly to water. The reactivity of cytochrome c-553 with the soluble peroxidase and the membrane-bound cytochrome-c oxidase was consistent with this cytochrome operating as physiological electron donor to both enzyme systems. The cytochrome-c peroxidase was partially purified and some of its properties determined. The cytochrome-c oxidase and formate oxidase were both membrane-bound and exhibited a high affinity for oxygen. Hydrogen peroxide was produced during the oxidation of formate, and accumulated when electron flow to the cytochrome-c peroxidase was inhibited. The capacity for hydrogen peroxide production was shown to be higher in young cells. The levels of cytochrome c-553 and of the peroxidase were higher in cells harvested earlier in growth. In cells harvested later in growth, the levels of cytochrome-c oxidase increased and the levels of c-553 decreased. A proton gradient with lower external pH was developed with either hydrogen or formate as electron donor, and either oxygen or hydrogen peroxide as the terminal electron acceptor. A respiratory role for hydrogen peroxide in this catalase-negative organism was proposed and discussed in relation to its microaerophilic nature. Haem-stained SDS-PAGE gels was one of the methods used to quantify cytochrome c-553. This method was shown to be generally applicable to the quantification of c-type cytochromes and to be useful during investigations into the induction and location of bacterial cytochromes-c.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Bacterial respiratory systems