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Frontiers in Nutrition

Food Microbiology

Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Nutr. | doi: 10.3389/fnut.2019.00152

Use of Mass Spectrometry to Profile Whey Peptides with Antivirulence Effect Against Salmonella enterica subsp. enterica Serovar Typhimurium

 Eman Ali1, 2,  Søren Drud Nielsen3, Salah Abd-El Aal4, Ahlam El-Leboudy5, Ebeed Saleh1 and  Gisele LaPointe2, 6*
  • 1Department of Food Hygiene, Faculty of Veterinary Medicine, Damanhour University, Egypt
  • 2Canadian Research Institute in Food Safety (CRIFS), Canada
  • 3Department of Food, Faculty of Science and Technology, Aarhus University, Denmark
  • 4Faculty of Veterinary Medicine, Zagazig University, Egypt
  • 5Department of Food Hygiene, Faculty of Veterinary Medicine, Alexandria University, Egypt
  • 6Department of Food Science, University of Guelph, Canada

Peptides in the 3-kDa ultrafiltrate of fermented whey protein isolate (WPI) medium could be responsible for the antivirulence activity of Lactobacillus helveticus LH-2 and Lactobacillus acidophilus La-5 against Salmonella Typhimurium. Non-fermented and fermented media containing 5.6% WPI were fractionated at a 3 kDa cut-off and the filtrate was analyzed by mass spectrometry. The non-fermented WPI medium contained 109 milk derived peptides, which originated from beta-casein (52), alpha s1-casein (22), alpha s2-casein (10), kappa-casein (8) and beta-lactoglobulin (17). Most of these peptides were not found in the fermented media, except for 14 peptides from beta-casein and one peptide from alpha s2-casein. Database searches confirmed that 39 out of the 109 peptides had established physiological functions, including angiotensin-converting-enzyme (ACE) inhibitory, antioxidant, antimicrobial, or immunomodulating activity. A total of 75 peptides were found in the LH-2 cell free spent medium (CFSM): 54 from beta-casein, 14 from kappa-casein, 4 from beta-lactoglobulin and 3 from alpha s2-casein. From these peptides, 19 have previously been associated with several categories of bioactivity. For La-5 CFSM, a total of 15 peptides were sequenced: 8 from beta-casein, 5 from alpha s1-casein, 2 from beta-lactoglobulin. Only 5 of these have previously been reported as having bioactivity. Many of the peptides remaining in the fermented medium contain low-affinity residues for oligopeptide binding proteins and higher resistance to peptidase hydrolysis. These properties of the sequenced peptides could explain their accumulation after fermentation despite the active proteolytic enzymes of LH-2 and La-5 strains. Down-regulated expression of hilA and ssrB genes in S. Typhimurium was observed in the presence of La-5 and LH-2 CFSM. Downregulation was not observed for the Salmonella oppA mutant strain exposed to the same CFSM used to treat the S. Typhimurium DT104 wild-type strain. This result suggests the importance of peptide transport by S. Typhimurium for down regulation of virulence genes in Salmonella.

Keywords: Bioactive peptide, probiotic, whey, Salmonella, Virulence

Received: 22 Oct 2018; Accepted: 06 Sep 2019.

Copyright: © 2019 Ali, Nielsen, Abd-El Aal, El-Leboudy, Saleh and LaPointe. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Gisele LaPointe, University of Guelph, Department of Food Science, Guelph, G1V 0A6, Québec, Canada, glapoint@uoguelph.ca