A novel antimicrobial peptide Cecropin from Hermetia illucens: Antibacterial activity, mode of action and application in pork preservation.

The increase in microbial antibiotic resistance combined with the growing concerns over potential safety risks of chemical preservatives have prompted the search for new classes of natural antimicrobial agents. AMPs present great potential for use in food preservation. This study investigated the antibacterial activities, modes of action, stability, in vivo protective effects, and practical application potential in pork preservation of a novel AMP Cecropin from Hermetia illucens (HiCec). HiCec is a 45-amino-acid cationic peptide with amphipathic structure. It showed broad-spectrum antibacterial activity, especially potent against Escherichia coli and Listeria monocytogenes with identical minimum inhibitory concentration of 0.64 μM. It killed bacteria through multiple modes of action: disrupting membrane integrity, increasing membrane permeability, impairing membrane potential, binding bacterial DNA, altering the expression levels of genes involved in bacterial DNA replication and repair, inducing the generation of intracellular reactive oxygen species. It maintained remarkable stable antibacterial activity under pH 2-10 and 4-90 °C, with negligible hemolysis and non-cytotoxicity. HiCec treatment significantly improved larvae survival and reduced bacterial loads in bacteria infected larvae. In chilled pork preservation, it significantly slowed pork sensory quality decline, inhibited bacterial growth, delayed pH increase, and reduced TVB-N and TBARS accumulation. Overall, HiCec's excellent antibacterial activity, stability, low toxicity and preservation potential make it a promising candidate for antibacterial agents and food preservatives.