Antimicrobial activity and mechanism of α-copaene against foodborne pathogenic bacteria and its application in beef soup

Abstract

Excessive use of traditional food preservatives has raised concerns about their adverse effects. α-Copaene is a natural terpene compound with excellent biological activity; however, the antibacterial activity and mechanism of α-copaene are unclear. Therefore, this study aimed to explore the antibacterial activity and mechanism of action of α-copaene against four common foodborne pathogens: Staphylococcus aureus, Escherichia coli, Bacillus cereus, and Shigella bogdii. α-Copaene inhibited bacterial growth with a minimum inhibitory concentration of 0.5–1 μL/mL and a minimum bactericidal concentration of 2–4 μL/mL. Scanning electron microscopy and flow cytometry showed morphological changes and damage to the cell membrane in cells treated with α-copaene. Confocal microscopy and cell content leakage further confirmed cell membrane damage and increased permeability caused by α-copaene treatment. α-Copaene suppressed biofilm formation by decreasing the hydrophobicity of the cell surface. Furthermore, the hemolytic activity and cytotoxicity assays showed that α-copaene had good biosafety. In conclusion, 4 μL/mL of α-copaene inhibited the growth of S. aureus, E. coli, B. cereus, and Sh. bogdii in beef soup. These results provide evidence of the antibacterial activity and mechanism of α-copaene and pave the way for developing α-copaene as a novel food preservative.