Identification and antimicrobial mechanisms of a novel peptide derived from egg white ovotransferrin hydrolysates

Ovotransferrin (OVT), displaying multiple bioactivities, is an important egg antimicrobial component. In this study, a novel antimicrobial peptide (OVTp12) was purified from the hydrolysate of OVT by ion-exchange chromatography, Sephadex G-15 gel filtration, and reversed-phase HPLC. The sequence of OVTp12 was identified as AGLAPYKLKPIA using LC-MS/MS with molecular mass of 1240.76 Da. Moreover, OVTp12 showed effective antimicrobial activity against both Gram-positive and Gram-negative bacteria (minimal inhibitory concentrations, MIC values = 32 - 128 mu g/mL). The outer/inner cell membrane permeabilization induced by OVTp12 indicated that the isolated peptide exhibited significant membrane permeability of Escherichia coli. To further reveal the antibacterial mechanism, CLSM and flow cytometry analyses demonstrated that OVTp12 could destroy cell membrane integrity and increase the permeability of pathogen's membrane. SEM analyses expressed that OVTp12 caused morphological changes in both Escherichia coli and Staphylococcus aureus. These results suggested that peptide OVTp12 from ovotransferrin may be a promising antimicrobial agent for food preservation or pharmaceuticals.