Antibacterial activity and mechanism of novel antimicrobial peptide KRR-N1-5W6L against Escherichia coli O157:H7 and Salmonella enterica and its application in pork preservation

Abstract

Escherichia coli O157:H7 and Salmonella enterica are foodborne pathogens that pose serious threats to pork safety and human health, highlighting the urgent need for effective and safe food preservatives. In this study, a novel antimicrobial peptide (AMP) named KRR-N1-5W6L was developed by modifying a natural AMP, N1, derived from buffalo colostrum whey. KRR-N1-5W6L exhibited potent antibacterial activity against E. coli O157:H7 and S. enterica with a minimum inhibitory concentration (MIC) of 32 μM, significantly lower than that of N1 (MIC >256 μM). Furthermore, KRR-N1-5W6L demonstrated remarkable thermal stability, pH stability (pH 6–9), and sensitivity to salts and proteases. Comprehensive analyses using multiple fluorescence probes, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) revealed that KRR-N1-5W6L disrupted the cell membranes of E. coli O157:H7 and S. enterica, leading to increased permeability of both outer and inner membranes, leakage of cellular contents, and dissipation of the proton motive force. Additionally, KRR-N1-5W6L was found to bind to DNA and induce the accumulation of intracellular reactive oxygen species (ROS) in both pathogens. Molecular docking studies indicated that KRR-N1-5W6L can bind to DNA gyrase via hydrogen bonds, thereby inhibiting pathogen growth. Moreover, KRR-N1-5W6L effectively delayed the quality deterioration of pork during storage at 4 °C, as evidenced by measurements of TVC, pH, TBARS, and color changes. These findings suggest that KRR-N1-5W6L holds promise as a potential food preservative for pork preservation.