Inhibitory impacts of essential oil (Zanthoxylum schinifolium Sieb. et Zucc) on the growth of Staphylococcus epidermidis

Abstract

Staphylococcus epidermidis is an important pathogenic microorganism with the ability to cause food contamination and clinical infections. Therefore, finding a green, safe and effective antimicrobial therapy will benefit food safety and public health. In this study, essential oil extracted from Zanthoxylum schinifolium Sieb. et Zucc was used to combat S. epidermidis. Zanthoxylum schinifolium Sieb. et Zucc essential oil (ZEO) showed excellent antibacterial activity with a minimum inhibitory concentration (MIC) of 2.5 mg/mL and a minimum bactericidal concentration (MBC) of 5.0 mg/mL. Meanwhile, single component antibacterial test results showed that the MIC values of the major components in ZEO, including linalool, dihydrolinalol, β-ocimene and nerolidol, ranged from 2.5 to 10 mg/mL. Evaluation of membrane permeability and integrity demonstrated that the pathogen had membrane damage and normal physiological function was impaired. Cell membrane potential and cell membrane fluidity analyses further revealed that ZEO induced increase in surface Zeta potential and cell membrane depolarization via electrostatic interactions with cell membrane; meanwhile, ZEO disordered lipid acyl chains and increased cell membrane fluidity to induce cell death. In addition, oxidative stress testing showed that ZEO can disrupt homeostasis of reactive oxygen species (ROS), causing ROS accumulation and increasing oxidative damage to cells. The destruction of cell morphology and ultrastructure by ZEO was further confirmed by electron microscopy. These results indicate that ZEO has the potential for development as an antibacterial agent to control the growth of S. epidermidis and prevent related infections.