Harris, Sarah Jane (2017) The influence of beta-glucans on the relationship between carp (Cyprinus carpio) and its associated microbiome. Doctoral thesis, Keele University.

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Abstract

Fish are in contact with microbiota from the moment of hatching. Exterior organs, i.e. skin, gills and intestinal system, are colonised by commensal bacteria populations and a symbiotic relationship is formed. The fish provides a niche and nutrients for the bacteria which stimulate development of the immune response, act as an additional barrier against invading pathogens and, within the gut, aid in digestion.

β-glucans are used within aquaculture as a means of improving fish health and can be applied in various forms, e.g. via diet or injection. Whilst the application of β-glucan is performed to modulate a fish’s immune system, it has also been shown to affect the gut microbiota population at concentrations above 1% w/w within the diet which is particularly important to consider when applied orally.

The effect of the commercially available β-glucan MacroGard® upon the gut of common carp (Cyprinus carpio) is studied after oral application and injection. Whilst
feeding with MacroGard® at 0.1% w/w within the diet does not influence the gut bacteria nor expression of bactericidal innate immune genes, injection (2mg kg-1 and
5mg kg-1) resulted in a 90% reduction in bacteria numbers in the gut after 24 hours.
Injection of MacroGard® did not significantly alter the expression of CRP, iNOS, bf/C2, IL-1β, ApoA1, HAMP1, LEAP2 and Muc2 within the gut however MSS1, a synthesised
β-glucan, significantly increased the gene expression of iNOS, CRP and Muc2. 0.1% MacroGard® in the diet was, however, capable of influencing bacterial species
diversity when injection was also performed. This revealed a high proportion of Alphaproteobacteria, which are typically associated with plants rather than gut systems, and corresponded with a reduction in potential pathogenic bacteria. This showed combining injection and oral application of MacroGard® together is capable of influencing the gut microbiota population within a 2 week period.

Item Type: Thesis (Doctoral)
Subjects: Q Science > QL Zoology
Divisions: Faculty of Natural Sciences > School of Life Sciences
Depositing User: Lisa Bailey
Date Deposited: 03 Mar 2017 15:49
Last Modified: 01 Jan 2020 01:30
URI: https://eprints.keele.ac.uk/id/eprint/2990

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