Evaluation of the Antibacterial and Prebiotic Potential of Ascophyllum nodosum and Its Extracts Using Selected Bacterial Members of the Pig Gastrointestinal Microbiota.

Brigkita Venardou,Gaurav Rajauria,Marion T Ryan,John V O’Doherty,Claire Kiely,Torres Sweeney,Marco Garcia-Vaquero,Mary J Mcdonnell

doi:10.3390/md20010041

Abstract

Ascophyllum nodosum and its extracts are promising antibacterial and prebiotic dietary supplements for pigs. The objectives of this study were to evaluate the effects of the increasing concentrations of: (1) two whole biomass samples of A. nodosum with different harvest seasons, February (ANWB-F) and November (ANWB-N), in a weaned pig faecal batch fermentation assay, and (2) A. nodosum extracts produced using four different extraction conditions of a hydrothermal-assisted extraction methodology (ANE1–4) and conventional extraction methods with water (ANWE) and ethanol (ANEE) as solvent in individual pure culture growth assays using a panel of beneficial and pathogenic bacterial strains. In the batch fermentation assay, ANWB-F reduced Bifidobacterium spp. counts (p < 0.05) while ANWB-N increased total bacterial counts and reduced Bifidobacterium spp. and Enterobacteriaceae counts (p < 0.05). Of the ANE1–4, produced from ANWB-F, ANWE and ANEE that were evaluated in the pure culture growth assays, the most interesting extracts were the ANE1 that reduced Salmonella Typhimurium, enterotoxigenic Escherichia coli and B. thermophilum counts and the ANE4 that stimulated B. thermophilum growth (p < 0.05). In conclusion, the extraction method and conditions influenced the bioactivities of the A. nodosum extracts with ANE1 and ANE4 exhibiting distinct antibacterial and prebiotic properties in vitro, respectively, that merit further exploration.

Highlights

Publisher’s Note: MDPI stays neutralThe gastrointestinal microbiota performs a wide range of biologically important functions for the host, such as increasing nutrient availability, immunomodulation and inhibition of pathogen colonisation [1,2,3]
A summary of preparation conditions for the whole biomass samples and extracts of A. nodosum that were utilised in this study is presented in Table 5, with further details as follows: Whole seaweed biomass: A. nodosum was harvested in February (ANWB-F) and November (ANWB-N) once and from the same collection site by Quality Sea Veg Ltd
The variation in the effects of the whole biomass samples of A. nodosum, ANWB-F and ANWB-N, on the counts of total bacteria, Bifidobacterium spp. and Enterobacteriaceae indicates that the harvest season may influence the presence of the associated bioactive components

Summary

Introduction

Publisher’s Note: MDPI stays neutralThe gastrointestinal microbiota performs a wide range of biologically important functions for the host, such as increasing nutrient availability, immunomodulation and inhibition of pathogen colonisation [1,2,3]. The Lactobacillus and Bifidobacterium genera are among the best-characterised beneficial members in terms of their contributions to these functions in a range of mammals, including humans and pigs [4,5,6,7,8,9]. Another important constituent is the Enterobacteriaceae family, as it harbours many pathogens such as pathogenic Escherichia coli strains and Salmonella enterica subsp. Disturbances in the composition of the gastrointestinal microbiota can result in dysbiosis, a transient or permanent pathological state, characterised by the loss of beneficial bacterial groups, the overgrowth of opportunistic pathogens and/or loss of overall microbial diversity [12].

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