Comparative chemical characterization and antibacterial evaluation of three Moroccan Lamiaceae essential oils against phytopathogenic bacteria

Abstract

Essential oils (EOs) obtained by hydrodistillation from Origanum elongatum , Thymus vulgaris , and Lavandula stoechas collected in Morocco’s Fez–Meknes region were chemically characterized and tested against six phyto-pathogenic bacteria: Erwinia amylovora , Pantoea ananatis , Pseudomonas viridiflava , Pseudomonas savastanoi , Allorhizobium vitis , and Pseudomonas marginalis . Their constituents were identified by gas chromatography coupled with mass spectrometry (GC–MS). At the same time, the antibacterial activity was evaluated using disc diffusion, microatmosphere, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) assays. Thymol and carvacrol predominated in O. elongatum EO. The principal constituents of L. stoechas EO were linalool (25.76%) and camphor (21.09%), whereas thymol accounted for 47.79% of T. vulgaris EO. Disc diffusion and microatmosphere assays demonstrated the antibacterial effects of O. elongatum and T. vulgaris EOs. The lowest MICs were obtained for O. elongatum EO (0.15–0.30 mg/mL), followed by T. vulgaris (0.30–1.25 mg/mL), and L. stoechas (10–20 mg/mL). Molecular docking indicated favorable interactions between the identi - fied constituents and bacterial target proteins, suggesting a molecular basis for the observed antibacterial effects. Overall, the present study suggests that O. elongatum and T. vulgaris EOs are promising plant-based candidates for further investigation in the management of bacterial plant diseases. However, their in planta efficacy, phytotoxicity, stability, and environmental safety require further evaluation before practical application.