Insight into the antibacterial activity of lauric arginate against Escherichia coli O157:H7: Membrane disruption and oxidative stress

Lauric arginate (LAE), an amino acid-based cationic surfactant, has recently attracted great attentions for applications in food preservation due to its antimicrobial properties. This work aimed to unravel the possible antibacterial mechanisms of LAE against Escherichia coli O157:H7. After exposure to LAE at 50 mu g/mL for 10 min, the microbial load decreased by 6.25-log units. According to the results of propidium iodide and N-phenyl-1napthylamine fluorescent staining, LAE severely damaged the cytoplasmic and outer membranes of E. coli O157: H7, leading to a loss of membrane integrity. An increase in DiBAC(4)(3) fluorescent intensity was observed in LAEtreated cells, indicating a rapid membrane depolarization. Lipopolysaccharide and peptidoglycan could effectively block LAE-triggered inactivation of E. coli O157:H7 cells, suggesting the binding of LAE with cell membrane components. Moreover, LAE also resulted in an increase in intracellular reactive oxygen species levels and the coadministration of antioxidants (such as ascorbic acid and glutathione) could effectively quench LAEmediated bacterial inactivation, indicating that oxidative stress was involved in the antibacterial action of LAE. In summary, the antibacterial activity of LAE against bacteria may be associated with a combined action of membrane damage and oxidative stress. This study provides a better understanding of the antibacterial mechanism of LAE.

Automated summary

This study reveals the antibacterial mechanism of lauric arginate (LAE) against Escherichia coli. LAE damages the cytoplasmic and outer membranes of E. coli, causing a loss of membrane integrity. It also induces oxidative stress and increases reactive oxygen species levels. The combination of membrane damage and oxidative stress contributes to the antibacterial activity of LAE.