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Effects of polysaccharide rich extracts obtained from the brown seaweed Laminaria digitata on human microbiota in an in vitro model of the distal colon

Published online by Cambridge University Press:  15 April 2015

C. R. Strain
Affiliation:
Northern Ireland Centre for Food And Health, School of Biomedical Sciences, University of Ulster, Coleraine BT52 1SA, UK
K. C. Collins
Affiliation:
Teagasc Food Research Centre, Moorepark, Fermoy, Republic of Ireland
T. J. Smyth
Affiliation:
Teagasc Ashtown Food Research Centre, Dublin, Republic of Ireland.
A. Soler-Vila
Affiliation:
Irish Seaweed Research Group, Ryan Institute, NUI Galway, Galway, Republic of Ireland
M. C. Rea
Affiliation:
Teagasc Food Research Centre, Moorepark, Fermoy, Republic of Ireland Alimentary Pharmabiotic Centre, University College Cork, Cork, Republic of Ireland.
C. Stanton
Affiliation:
Teagasc Food Research Centre, Moorepark, Fermoy, Republic of Ireland Alimentary Pharmabiotic Centre, University College Cork, Cork, Republic of Ireland.
R. P. Ross
Affiliation:
Teagasc Food Research Centre, Moorepark, Fermoy, Republic of Ireland Alimentary Pharmabiotic Centre, University College Cork, Cork, Republic of Ireland.
P. J. Allsopp
Affiliation:
Northern Ireland Centre for Food And Health, School of Biomedical Sciences, University of Ulster, Coleraine BT52 1SA, UK
V. Naughton
Affiliation:
Northern Ireland Centre for Food And Health, School of Biomedical Sciences, University of Ulster, Coleraine BT52 1SA, UK
E. M. McSorley
Affiliation:
Northern Ireland Centre for Food And Health, School of Biomedical Sciences, University of Ulster, Coleraine BT52 1SA, UK
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Abstract

Type
Abstract
Copyright
Copyright © The Authors 2015 

Brown macroalgae are rich in a number of unique polysaccharides such as laminarin, fucoidan and alginate(Reference Gupta and Abu-Ghannam1). Several of these polysaccharides have demonstrated some activity with respect to stimulating beneficial gut bacteria and positively altering the metabolic activity of gut bacterial species(Reference An, Kuda and Yazaki2, Reference Devillé, Gharbi and Dandrifosse3, Reference O'Sullivan, Murphy and McLoughlin4). Laminaria digitata (LD) is a common Irish brown seaweed and is a rich source of such polysaccharides. Therefore, the aim of this study was to extract these polysaccharides from LD and assess the effects on human faecal microbiota using an in vitro colonic model.

LD was harvested off the west coast of Ireland during July 2012. Polysaccharides were extracted using hot acid and ethanol precipitation. The extract was then either depolymerised (DE) or not (Crude, CE), before undergoing a simulated in vitro digestion followed by size exclusion chromatography to remove simple sugars. The extracts were fermented (n = 3) in anaerobic batch culture vessels with human faecal bacterial populations sourced from three healthy volunteers. Samples were removed at 0, 5, 10, 24, 36 and 48 hour time points before undergoing culture dependent analysis of bifidobacteria and lactobacillus populations, and analysis of Short chain fatty acids using GC-FID.

Both extracts demonstrated some degree of fermentation, with both extracts significantly increasing total SCFA levels. Furthermore CE extract significantly increased both butyrate and propionate concentrations, while DE significantly increased propionate concentration. Neither extract was found to increase culturable Bifidobacteria and Lactobacillus populations. This study has demonstrated that both crude polysaccharides and depolymerised polysaccharides derived from LD affect the metabolic activities of human faecal microbiota. Further work is required to identify the microorganisms associated with these activities.

References

1.Gupta, S & Abu-Ghannam, N (2011) Trends Food Sci Tec 22, 315–216.Google Scholar
2.An, C, Kuda, T, Yazaki, T et al. (2013) Appl Environ Microbiol 79, 860866.Google Scholar
3.Devillé, C, Gharbi, M, Dandrifosse, G et al. (2007) J. Sci. Food Agric 87, 17171725.Google Scholar
4.O'Sullivan, L, Murphy, B, McLoughlin, P et al. (2010) Mar Drugs 8, 20382064.Google Scholar