Antilisterial activity of Thymus vulgaris essential oil: In vitro, in situ, and in silico investigations

Listeria monocytogenes is a major foodborne pathogen that significantly threatens public health and food safety. While Thymus vulgaris essential oil (TV-EO) is widely recognized for its potent antibacterial activity, its specific effects against L. monocytogenes remain unexplored. This study aimed to assess the antilisterial activity of TV-EO using in vitro, in situ, and in silico approaches. The in vitro assessment included disc diffusion method, determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), biofilm inhibition assay, and predictive modeling to assess L. monocytogenes reduction in the presence of TV-EO at 10 °C and 20 °C. In situ approach evaluated the inhibitory effect of TV-EO on L. monocytogenes in minced poultry meat stored at 4 °C. Finally, in silico approach, based on molecular docking, was employed to evaluate the binding affinity of major TV-EO components for β-ketoacyl-ACP synthase II and chorismate synthase, key proteins involved in fatty acid biosynthesis and biofilm formation, respectively. Our finding revealed that TV-EO exhibited strong in vitro antilisterial activity, with inhibitory zones ranging from 51.00 ± 1.00 mm to 55.67 ± 1.15 mm, a MIC value of 0.125 %, and a MBC value of 0.25 %, indicating its bactericidal effect. TV-EO at 0.125 % demonstrated a high capacity to inhibit and eradicate the biofilm, with 100 ± 0.00 % and 91.33 ± 1.23 %, respectively. Predictive modeling, based on the combination of TV-EO and ζ values, revealed that L. monocytogenes inactivation was more pronounced at low temperature. Furthermore, the in-situ approach showed a significant reduction of L. monocytogenes amount, with decreases of 1.068 ± 0.132 log cfu/g, 0.671 ± 0.091 log cfu/g, and 0.317 ± 0.029 log cfu/g at TV-EO concentrations of 1 %, 0.5 %, and 0.25 %, respectively (p < 0.05). In silico analysis indicated that TV-EO components, particularly carvacrol, exhibited high affinity for β-ketoacyl-ACP synthase II and chorismate cynthase, suggesting strong antilisterial and ani-biofilm activity. These findings highlight the antilisterial efficacy of TV-EO, demonstrating its potential as a natural alternative to conventional preservatives for enhancing food preservation and safety.