Isolation, identification, and mode of action of antibacterial peptides derived from egg yolk hydrolysate

Thippawan Pimchan; Fu Tian; Kanjana Thumanu; Sureelak Rodtong; Jirawat Yongsawatdigul

doi:10.1016/j.psj.2023.102695

Isolation, identification, and mode of action of antibacterial peptides derived from egg yolk hydrolysate

Poult Sci. 2023 Jul;102(7):102695. doi: 10.1016/j.psj.2023.102695. Epub 2023 Apr 5.

Authors

Thippawan Pimchan¹, Fu Tian¹, Kanjana Thumanu², Sureelak Rodtong³, Jirawat Yongsawatdigul⁴

Affiliations

¹ School of Food Technology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand.
² Synchrotron Light Research Institute (Public Organization), Nakhon Ratchasima, 30000, Thailand.
³ School of Preclinical Sciences, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand.
⁴ School of Food Technology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand. Electronic address: jirawat@sut.ac.th.

Abstract

Egg yolk is a coproduct of egg white processing. The protein hydrolysis of egg yolks to exhibit antimicrobial activity is a strategy for its valorization. The objective of this study is to fractionate antibacterial peptides from pepsin-hydrolyzed egg yolks using flash chromatography. In addition, the mode of actions of the fractionated peptides were elucidated and plausible antibacterial peptides were reported. The fraction 6 (F6) obtained from a C18-flash column exhibited antibacterial activity against Staphylococcus aureus ATCC 29213 and Salmonella typhimurium TISTR 292 at minimal inhibitory concentration (MIC) values of 0.5 to 1 mmol/L (Leucine equivalent). The fractionated peptides induced DNA leakage as monitored by 260 nm. Propidium iodide and SYTO9 staining observed under a confocal microscope suggested the disintegration of cell membranes. Synchrotron-based Fourier-transform infrared spectroscopy analysis revealed that the egg yolk peptides at 1 × MIC induced an alteration of phospholipids at cell membranes and modified conformation of intracellular proteins and nucleic acids. Scanning electron microscopy revealed obvious cell ruptures when S. aureus was treated at 1 × MIC for 4 h, whereas damage of cell membranes and leakage of intracellular components were also observed for the transmission electron microscopy. Egg yolk peptides showed no hemolytic activity in human erythrocytes at concentrations up to 4 mmol/L. Peptide identification by LC-MS/MS revealed 3 cationic and 10 anionic peptides with 100% sequence similarity to apolipoprotein-B of Gallus gallus with hydrophobicity ranging from 27 to 75%. The identified peptide KGGDLGLFEPTL exhibited the highest antibacterial activity toward S. aureus at MIC of 2 mmol/L. Peptides derived from egg yolk hydrolysate present significant potential as antistaphylococcal agents for food and/or pharmaceutical application.

Keywords: antibacterial peptide; egg yolk; flash chromatography; mechanism; protein hydrolysate.

MeSH terms

Animals
Anti-Bacterial Agents / chemistry
Anti-Bacterial Agents / pharmacology
Chickens
Chromatography, Liquid / veterinary
Egg Yolk*
Humans
Microbial Sensitivity Tests / veterinary
Peptides / chemistry
Staphylococcus aureus*
Tandem Mass Spectrometry / veterinary

Substances

Peptides
Anti-Bacterial Agents