Comparison of Wild and Field-Cultivated Thymus satureioides: Effects on Rhizosphere Properties, Essential-Oil Composition, and Biological Activities

Thymus satureioides Coss. is an endemic Moroccan medicinal and aromatic species of high socio-economic value, is increasingly threatened by overexploitation and continued reliance on wild harvesting. Sustainable cultivation could reduce pressure on natural populations, yet its effects on essential oil (EO) composition, bioactivity, and associated microbial diversity remain poorly understood. This study compared EO yield, chemical composition, antioxidant, antimicrobial, and nematicidal activities, and soil microbial diversity (PLFA) between wild (WT) and cultivated (CT) populations. Gas chromatography–MS analysis identified 18 and 24 compounds in WT-EO and CT-EO, respectively. Thymol and endo-borneol were the major constituents in both oils, with thymol occurring at higher levels in CT-EO (31.83%) than WT-EO (24.79%), while endo-borneol accounted for 15.61% and 16.37%, respectively. WT-EO was further characterized by the exclusive presence of camphor (0.28%). Despite the higher EO yield in CT plants, WT-EO exhibited stronger biological activities. WT-EO showed significantly higher antioxidant capacity, with lower IC50 values than CT-EO in TAC (0.01 vs. 0.02 mg mL−1), DPPH (0.30 vs. 0.60 mg mL−1), and ABTS (0.03 vs. 0.37 mg mL−1) assays. WT-EO also showed stronger antimicrobial activity, with lower MIC values against E. coli (2.5 vs. 3.8 mg mL−1), Pseudomonas aeruginosa (2.5 vs. 3.8 mg mL−1), and Staphylococcus aureus (0.04 vs. 0.50 mg mL−1). At the lowest tested concentration (5 µL mL−1), WT-EO induced significantly higher nematicidal activity than CT-EO, although both oils reached nearly complete juvenile mortality and egg-hatching inhibition at higher concentrations. WT soils also supported greater microbial biomass and a distinct PLFA-based microbial profile than CT soils (9.53 vs. 3.77 µg g−1 soil). These findings support cultivation as a sustainable production strategy while highlighting the importance of conserving WT populations as reservoirs of chemical and microbial diversity.