Antibacterial Activity and Mechanism of a Bacteriocin Derived from the Valine-Cecropin A(1–8)-Plantaricin ZJ5(1–18) Hybrid Peptide Against Escherichia coli O104

Peptide fragment hybridization is an effective method to obtain novel hybrid antimicrobial peptides with higher antibacterial activities. The novel peptide, valine-cecropin A(1–8)-plantaricin ZJ5(1–18) (CA-P), was designed by coupling the amphiphilic N-terminal fragment of CA with the N-terminal core helix of P and adding a valine residue to the N-terminus of the hybrid fragment. CA-P showed higher antibacterial activities than the parental peptide P against all indicator strains in the experiment, with no hemolytic activity against sheep red blood cells. Observations by scanning electron microscopy and transmission electron microscopy confirmed that CA-P destroyed the surface structure of the bacteria and caused leakage of the cellular contents. As determined by fluorescence microscopy, the antibacterial mechanism of CA-P is microorganism killing. It was observed that CA-P and Litsea mollis Hemsl. essential oil showed a significant synergistic effect against Salmonella enterica serovar Newport.