Linalool against Hafnia alvei, its antibacterial mechanism revealed by metabolomic analyses

Linalool, a major component of aromatic plant essential oils, has an antibacterial effect against Hafnia alvei, which can induce food spoilage. In this study, we aimed to investigate the antibacterial effect and mechanism of linalool against H. alvei. Linalool treatment resulted in excessive reactive oxygen species (ROS) accumulation, which resulted in destruction of the cell membrane. According to the field emission scanning electron microscopy (FESEM) and flow cytometry (FCM) results, it was confirmed that the membrane structure of H. alvei was destroyed. Moreover, metabolomics analysis showed that there were 64 and 73 differentially expressed metabolites screened by mass spectrometry in positive and negative ion modes, respectively, suggesting that nucleic acid metabolism, the respiratory chain and energy metabolism were negatively affected by linalool. Biochemical validation confirmed that the activities of malate dehydrogenase (MDH), and succinate dehydrogenase (SDH) and respiratory metabolism were reduced after linalool treatment. It was therefore concluded that the cell membrane was damaged, nucleic acid metabolism was disturbed, and energy metabolism was reduced by inhibition of the respiratory chain and tricarboxylic acid (TCA) cycle. These results revealed the antibacterial mechanism of linalool against H. alvei, and support the use of linalool as a potential natural preservative to control H. alvei.