Unveiling the anti-listerial effect of Citrus bergamia essential oil: Mechanism of membrane disruption and anti-hemolytic activity

Listeria monocytogenes is a prominent cause of foodborne illnesses and public health concerns worldwide. Naturally active compounds have been extensively explored for their potential to reduce foodborne pathogenic contamination. This work is designed to study the chemical composition, antibacterial effect , and inhibition mechanism of Citrus bergamia essential oil (CB-EO) against L. monocytogenes . The CB-EO composition revealed the major components of the total account are d -limonene (23.2%), linalyl acetate (14.01%), and linalool (9.96%). The inhibitory effect was examined at different concentrations of CB-EO, and the MIC value was 1.5 mg/mL against L. monocytogenes . The CB-EO concentration of 1.5 mg/mL significantly disturbed the membrane permeability and fluidity, leading to leakage of intracellular protein and DNA constituents, as revealed by the BCA protein assay and UV–Vis spectrophotometric analysis, respectively. However, a decrease in concentration to 0.75 mg/mL indicated a significant decline in intracellular macromolecule leakage as well as membrane disruption. Moreover, SEM and CLSM observations provided extensive insight into the inhibition mechanism of CB-EO against L. monocytogenes . Finally, while investigating the anti-hemolysis activity, CB-EO and its major compounds, limonene , linalool, and linalyle acetate, have been found to be effective against the virulence agent listeriolysin O (LLO). Thus, it was proposed that CB-EO could act on L. monocytogenes cells through multiple mechanisms of action, with EO concentration providing a crucial role in determining the mode of action. This work offers deep insight into the inhibition mechanisms of natural substances, expanding the potential uses of CB-EO as a natural antimicrobial.