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    Production and characterisation of yeast cell wall preparations with binding activity against Salmonella and Escherichia coli.


    Griffin, Steven (2015) Production and characterisation of yeast cell wall preparations with binding activity against Salmonella and Escherichia coli. PhD thesis, National University of Ireland Maynooth.

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    Abstract

    A rise in food safety and production standards (e.g. the ban on antibiotics) has led to a search for alternative natural products to achieve a high yielding, safe method of meat production. Mannan oligosaccharides (MOS) are one such class of product that can potentially provide this. Abundant in the cell wall of Saccharomyces cerevisiae as well as other yeast species, MOS have the capacity to inhibit type 1 fimbriae containing pathogenic bacteria from binding to host tissue and thus prevent infection. Alterations in the growing conditions of several yeast strains, including Saccharomyces, Kluyveromyces, Candida, Schizosaccharomyces, Pichia, and Rhodotorula were examined to determine if by varying simple fermentation constituents it was possible to change yeast cell wall composition and increase its MOS content. The cell wall monosaccharide content (e.g. glucose and mannose) of a number of samples was significantly altered depending on the sole carbon source in the growth medium. However, the effect of carbon source on the cell wall monosaccharide content was strain specific. A quantitative assay to assess the efficacy of MOS type products to bind bacteria in vitro was developed. Initially, agglutination of bacteria to MOS was observed on a microscope slide for a number of type 1 fimbriae containing strains of Salmonella and Escherichia coli. The method was transferred to a 96 well plate format and optimised. The binding activity assay was shown to be repeatable and reproducible for Salmonella and E. coli strains. Yeast cell wall samples generated in this study were screened using the developed assay. S. cerevisiae 695, K. lactis 752, and Schiz. pombe 70572 cell wall samples had significantly higher binding activity than the control MOS used to develop the assay. The relationship between the yeast cell wall saccharide content and binding activity varied between strains indicating that the structure and not necessarily the quantity of the saccharides were more important in binding type 1 fimbriae containing bacteria. Analysis of the N-glycan profile of the samples with high binding activity revealed the presence of both common and unique mannan oligosaccharides. These unique mannan oligosaccharides may be responsible for the increased binding activity of these samples.

    Item Type: Thesis (PhD)
    Keywords: Production; characterisation; yeast cell wall preparations; binding activity; Salmonella; Escherichia coli;
    Academic Unit: Faculty of Science and Engineering > Biology
    Item ID: 10384
    Depositing User: IR eTheses
    Date Deposited: 07 Jan 2019 15:38
    URI:

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