Isolation, Purification and Stability of Antimicrobial Peptides from Walnut Glutenin

Abstract

Objective: To prepare antimicrobial peptides (AMPs) as a new alternative to antibiotics from walnut glutenin. Methods: AMPs were prepared by solid-state fermentation using Bacillus subtilis synchronized with alkaline protease treatment, separated, purified, and screened by successive ultrafiltration, gel filtration chromatography, liquid chromatography-tandem mass spectrometry (LC-MS/MS) and molecular docking. The stability of AMPs was studied by using Escherichia coli and Staphylococcus aureus as indicator strains. Results: fractions WGP-IIIA and WGP-IIIC, obtained after gel filtration chromatography, had strong antibacterial activity. By LC-MS/MS combined with virtual screening, 6 peptides were identified from the 2 fractions, and 3 peptides were obtained by molecular docking, namely LAEAYNIPDTIARRL from WGP-IIIA and SHSVIYVIR and APQLLYIVK from WGP-IIIC. The results of molecular docking showed that the antibacterial activity of WGP-IIIC was stronger. The AMPs were stable to high temperature, ultraviolet light, varying pH and different proteases. Conclusion: Walnut AMPs have application value in the field of food preservation.

Keywords

• glutenin-derived antimicrobial peptides; synchronous fermentation and enzymatic treatment; isolation and purification; bacteriostatic stability; molecular docking