Mechanism of membrane damage to Shigella sonnei by linalool from plant essential oils: A driver of oxidative stress

This work explored the antibacterial mechanism of linalool on Shigella sonnei (S. sonnei) based on membrane damage driven by oxidative stress. The results revealed that linalool had excellent inhibition towards S. sonnei under a concentration of 1.5 mL/L. Furthermore, cell structure was disrupted with massive leakage of K+ and Mg2+ with linalool according to scanning electron microscopy, zeta potential and probes staining of fluorescein diacetate and Rhodamine 123 combined with fluorescence spectroscopy. Changes in membrane protein conformation were also monitored as a result of fluorescence spectroscopy when exposed to linalool. In addition, oxidative stress was appeared after exposure to linalool due to the increase of malondialdehyde, hydrogen peroxide, superoxide anion and oxidized glutathione, and the decrease of reduced glutathione. The activity of defense enzyme including superoxide dismutase, catalase and peroxidase, and antioxidant enzyme including glutathione reductase and glutathione S-transferase was also inhibited. In all, oxidative stress-driven membrane damage was considered as the main mechanism by which linalool inhibited S. sonnei. Our findings provide theoretical support for linalool as a promising natural antibacterial agent against S. sonnei contamination.