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Campylobacter jejuni: Viability and Association with Food-Processing Surfaces.

Boucher, Stephanie. (1995) Campylobacter jejuni: Viability and Association with Food-Processing Surfaces. Doctoral thesis, University of Surrey (United Kingdom)..

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The relationship between culturability, survival and the coccoid form of Campylobacter jejuni was investigated using two clinical isolates. The existence of a viable, non-culturable state was studied using a range of techniques. The Direct Viable Count procedure of Rollins & Colwell (1986) was found to be unsatisfactory, as its interpretation was never clear cut. Using vital stains based on the ability of respiring cells to reduce tetrazolium salts to coloured and fluorescent indicators, evidence was found of residual respiratory activity in non-culturable coccoid and spiral cells. This activity was harder to detect as cells aged, indicating a running down of cellular activity. The results suggested that the coccoid form was not a stable viable non-culturable state but rather a degenerative form of the dying organism. It was not possible to induce reversion of the non-culturable respiring cells back to a culturable state by passage through gnotobiotic rats containing a human gut flora. However, the failure to isolate the organism from control faeces and caecum after feeding culturable cells indicated that refinement of the experimental protocol was necessary before this issue could be resolved. A block of beech wood added to the broth cultures apparently had a protective effect by causing large numbers of culturable cells to be maintained for several weeks under conditions which, in the absence of wood, would have become non-culturable within 48 hours. Several possible mechanisms for this protective effect were investigated including the possible role of free-radical scavenging, the form and dimensions of voids in wood, glass and other relevant domestic materials, and the effects of scored surfaces. A novel test method for detecting the levels of certain free radicals was developed using Galvinoxyl, however, the efficacy was impaired by poor interface transport kinetics. The void structures in beech wood and other materials showed that only voids with certain critical dimensions appeared to have the protective effect. The relevance of these materials in food hygiene terms is considered and an explanation offered for the unexpected longevity of Campylobacter jejuni in domestic environments.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors : Boucher, Stephanie.
Date : 1995
Additional Information : Thesis (Ph.D.)--University of Surrey (United Kingdom), 1995.
Depositing User : EPrints Services
Date Deposited : 24 Apr 2020 15:27
Last Modified : 24 Apr 2020 15:27

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