Revealing the composition and mechanism of the antibacterial activity of essential oil from the fruits of Litsea mollis Hemsl.

Abstract

Essential oils (EOs) have received increasing attention due to their safety and effective antibacterial activity. The chemical components and antibacterial activity of Litsea mollis Hemsl. essential oil no. 2 (LMEO2) was investigated in the present work. GC-MS analysis was performed, and 24 bioactive compounds were detected with citral being the most predominant (46.1482%). LMEO2 had high antibacterial activity against the foodborne pathogens Escherichia coli O157 and Salmonella Enteritidis. The minimum inhibitory concentration (MIC) was 0.01% for E. coli O157, and 0.05% for Salmonella Enteritidis, and the minimum bactericidal concentration (MBC) was 0.05% for E. coli O157, and 0.1% for Salmonella Enteritidis. Furthermore, the alkaline phosphatase (AKP) leak assays revealed that LMEO2 destroyed the integrity of cell wall. This was consistent with the nucleic acid leakage assays which revealed that LMEO2 enhanced the membrane permeability. Meanwhile, the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) assays also demonstrated that LMEO2 could damage the cell wall integrity, thus leading to cellular content leakage. The main bioactive component of LMEO2 was citral. LMEO2 could be a promising plant-derived antibacterial agent.