Effects of a dietary β-(1,3)(1,6)-D-glucan supplementation on intestinal microbial communities and intestinal ultrastructure of mirror carp (Cyprinus carpio L.).

H. Kühlwein*, M. J. Emery, M. D. Rawling, G. M. Harper, D. L. Merrifield, S. J. Davies

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

AIM: To assess the effects of dietary Saccharomyces cerevisiae β-(1,3)(1,6)-D-glucan supplementation (MacroGard(®)) on mirror carp (Cyprinus carpio L.) intestinal microbiota and ultrastructure of the enterocyte apical brush border. METHODS AND RESULTS: Carp were fed either a control diet or diets supplemented with 0.1, 1 or 2% w/w MacroGard(®). Culture-dependent microbiology revealed that aerobic heterotrophic bacterial levels were unaffected by dietary MacroGard(®) after 2 and 4 weeks. No effects were observed on the allochthonous lactic acid bacteria (LAB) populations at either time point; however, reduced autochthonous LAB populations were observed at week 4. PCR-DGGE confirmed these findings through a reduction in the abundance of autochthonous Lactococcus sp. and Vagococcus sp. in MacroGard(®)--fed fish compared with the control-fed fish. Overall, sequence analysis detected microbiota belonging to the phyla Proteobacteria, Firmicutes, Fusobacteria and unidentified uncultured bacteria. DGGE analyses also revealed that dietary MacroGard(®) reduced the number of observed taxonomical units (OTUs) and the species richness of the allochthonous microbiota after 2 weeks, but not after 4 weeks. In contrast, dietary MacroGard(®) reduced the number of OTUs, the species richness and diversity of the autochthonous microbiota after 2 weeks, and those parameters remained reduced after 4 weeks. Transmission electron microscopy revealed that intestinal microvilli length and density were significantly increased after 4 weeks in fish fed diets supplemented with 1% MacroGard(®). CONCLUSIONS: This study indicates that dietary MacroGard(®) supplementation modulates intestinal microbial communities of mirror carp and influences the morphology of the apical brush border. SIGNIFICANCE AND IMPACT OF THE STUDY: To the authors' knowledge, this is the first study to investigate the effects of β-(1,3)(1,6)-D-glucans on fish gut microbial communities, using culture-independent methods, and the ultrastructure of the apical brush border of the enterocytes in fish. This prebiotic-type effect may help to explain the mechanisms in which β-glucans provide benefits when fed to fish.
Original languageEnglish
Pages (from-to)1091-1106
Number of pages0
JournalJ Appl Microbiol
Volume115
Issue number5
DOIs
Publication statusPublished - Nov 2013

Keywords

  • PCR-DGGE
  • common carp
  • culturable
  • electron microscopy
  • gut microbiota
  • immunostimulants
  • intestinal ultrastructure
  • Animal Feed
  • Animals
  • Bacteria
  • Carps
  • Denaturing Gradient Gel Electrophoresis
  • Dietary Supplements
  • Glucans
  • Intestines
  • Microbiota
  • Microscopy
  • Electron
  • Transmission
  • Microvilli
  • Polymerase Chain Reaction
  • Prebiotics

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