Evaluation of the in vitro effects of the increasing inclusion levels of yeast β-glucan, a casein hydrolysate and its 5 kDa retentate on selected bacterial populations and strains commonly found in the gastrointestinal tract of pigs.

Brigkita Venardou,Torres Sweeney,John V O'Doherty,Marion T Ryan,Claire Kiely,Anindya Mukhopadhya,Mary J Mcdonnell

doi:10.1039/d0fo02269a

Brigkita Venardou, Torres Sweeney + Show 5 more

Open Access

https://doi.org/10.1039/d0fo02269a

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Abstract

Previously, the 5 kDa retentate (5kDaR) of a casein hydrolysate (CH) and yeast β-glucan (YBG) were identified as promising anti-inflammatory dietary supplements for supporting intestinal health in pigs post-weaning. However, their direct effects on intestinal bacterial populations are less well-known. The main objectives of this study were to determine if the increasing concentrations of the CH, 5kDaR and YBG individually, can: (1) alter the bacterial and short-chain fatty acid profiles in a weaned pig faecal batch fermentation assay, and (2) directly influence the growth of selected beneficial (Lactobacillus plantarum, L. reuteri, Bifidobacterium thermophilum) and pathogenic (Enterotoxigenic Escherichia coli, Salmonella Typhimurium) bacterial strains in individual pure culture growth assays. The potential of CH as a comparable 5kDaR substitute was also evaluated. The 5kDaR increased lactobacilli counts and butyrate concentration in the batch fermentation assay (P < 0.05) and increased L. plantarum (linear, P < 0.05), L. reuteri (quadratic, P < 0.05) and B. thermophilum (linear, P < 0.05) counts and reduced S. typhimurium (quadratic, P = 0.058) counts in the pure culture growth assays. CH increased butyrate concentration (P < 0.05) in the batch fermentation assay. YBG reduced Prevotella spp. counts (P < 0.05) and butyrate concentration (P < 0.05) in the batch fermentation assay. Both CH and YBG had no major effects in the pure culture growth assays. In conclusion, the 5kDaR had the most beneficial effects associated with increased counts of Lactobacillus and Bifidobacterium genera and butyrate production and reduced S. typhimurium counts in vitro indicating its potential to promote gastrointestinal health.

Highlights

Diet is an important driver of the composition of the gastrointestinal microbiota
The ability of the batch fermentation assay to maintain a complex faecal bacterial community was evaluated by determining the changes in the counts of the selected bacterial groups in 2192 | Food Funct., 2021, 12, 2189–2200
The addition of 5 kDa retentate (5kDaR) in the batch fermentation and pure culture growth assays was consistently associated with increases in beneficial bacterial groups such as lactobacilli and B. thermophilum and a reduction in S. typhimurium. 5kDaR stimulated the production of butyrate in the batch fermentation assay, a major energy source and immunomodulatory molecule of the intestinal epithelium

Summary

Introduction

Diet is an important driver of the composition of the gastrointestinal microbiota. Extensive research has been carried out to identify dietary supplements which promote the growth ofPaper beneficial bacteria and/or inhibit the colonisation of pathogens. Of interest are the bioactive peptides derived from the bovine milk proteins, casein and whey. These peptides exhibit a broad range of biological activities such as antihypertensive,[15] antioxidative,[16] immunomodulatory[17,18,19] and antibacterial against various pathogenic and spoilage bacteria.[20,21,22,23,24] Another interesting finding is the growth-promoting and protective properties of milk bioactive peptides to beneficial bacteria such as Lactobacillus spp. and Bifidobacterium spp.[19,23,25,26] there is evidence that these bioactive peptides can be multifunctional. A casein peptide exhibiting antibacterial, antioxidant and antihypertensive capacity has been previously identified.[22]

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