The preservative potential of Octopus scraps peptides−Zinc chelate against Staphylococcus aureus: Its fabrication, antibacterial activity and action mode

A new type of zinc-chelating peptide was fabricated from Octopus scraps protein hydrolysate and its antibacterial activity against Staphylococcus aureus was characterized. Results of Fluorescence spectra and Fourier Transform Infrared Spectrometer (FT-IR) demonstrated that the amino nitrogen atoms and the oxygen atoms belonging to the carboxylate groups were the primary chelating sites for zinc ions. The zinc-peptide chelate exerted remarkably antimicrobial ability towards S. aureus , whose minimum inhibitory concentration (MIC) was 1.56 mg/mL. To investigate the antibacterial mechanism, changes of bacterial morphology, cell constituents, membrane potential, intracellular reactive oxygen species (ROS) level and intracellular enzyme activity were measured. Results revealed that Zn-peptide exerted its bactericidal activity by damaging bacterial cell membranes and cell walls, increasing the cell permeability which resulted in structural lesions and release of cell components. Besides, Zn-peptide induced S. aureus cell death via ROS triggered pathway. These findings further promote the development of Zn-peptide complexes, suggesting that Zn-peptide chelate has potential as natural bacteriostatic agent in food processing industry.