Abstract: In this paper, the antibacterial effect and mechanism of action caryophyllene against Brochothrix thermosphacta were studied. The inhibitory activity was investigated by determining the minimum inhibitory concentration (MIC) and growth curve. The degree of damage to cell morphology and cell wall structure caused by caryophyllene were determined respectively by using scanning electron microscopy (SEM) and measuring the leakage of alkaline phosphatase (AKP). The effect on the cell membrane was examined by measuring the leakage of potassium ions, fluorescein diacetate (FDA) and proteins. The effect on cell metabolism was investigated by measuring the activity of malate dehydrogenase (MDH) and pyruvate kinase (PK). The binding of caryophyllene to bacterial DNA was studied by fluorescence spectroscopy. The results showed that the MIC of caryophyllene against B. thermosphacta was 4.51 mg/mL. Caryophyllene at concentrations of 1 × MIC and 2 × MIC could destroy the morphology and structure of the cells and the permeability of the cell membrane, thus affecting cell metabolism, leading to a significant decrease in malate dehydrogenase and pyruvate kinase activities (P < 0.05), and destroying the conformation and structure of genomic DNA.

Key words: caryophyllene, Brochothrix thermosphacta, antibacterial mechanism, malate dehydrogenase, pyruvate kinase, genomic DNA