A hemoglobin-derived antimicrobial peptide, LCH4, from the large yellow croaker (Larimichthys crocea) with potential use as a food preservative

In this study, bioinformatics tools were used to predict potential antimicrobial peptides according to the hemoglobin sequence of the large yellow croaker (Larimichthys crocea). A novel antimicrobial peptide, designated as LCH4, was identified, and its antimicrobial effect and mechanism of action on Staphylococcus aureus and Vibrio parahaemolyticus were explored. The minimal inhibitory concentration (MIC) of LCH4 for S. aureus and V. parahaemolyticus was 12.5 mu g/mL and 25 mu g/mL, respectively. Transmission electron microscopy revealed that LCH4 killed bacteria by perforating their cell wall, resulting in the leakage of intracellular solutes and the consequent collapse of the cell membrane. In addition, LCH4 was able to increase the inner-membrane permeability of V. parahaemolyticus in a concentration-dependent manner and was also able to inhibit biofilm formation by S. aureus and V. parahaemolyticus by 88.0% and 75.0%, respectively, at 1 x MIC. Moreover, the LCH4 peptide had no cytotoxic effects on normal human hepatocytes, even at high concentrations (16 x MIC), with a cell survival rate of more than 93%. Most importantly, LCH4 had a strong inhibitory effect on the growth of pathogenic bacteria in soy sauce, which makes LCH4 a good candidate for broad application as a food preservative.