OICC Press Progress in Biomaterials 2194-0517 14 01 2025 03 31 Evaluation of Effects of Mycorrhizal fungi and Azotobacter Bacteria on Growth, Quantity, Quality, and Antimicrobial Properties of Essential Oil of Fennel plant Foeniculum vulgare Mill 10.57647/pibm.2025.142504 EN Mohaddeseh Larypoor Department of Microbiology, Faculty of Biological Sciences, NT.C., Islamic Azad University, Tehran, Iran Fatemeh Vasileh Izadmousa Department of Microbiology, Faculty of Biological Sciences, NT.C., Islamic Azad University, Tehran, Iran Hoora Dadgostar Department of Microbiology, Faculty of Biological Sciences, NT.C., Islamic Azad University, Tehran, Iran Shahrzad Sadeghi Amjad Department of Microbiology, Faculty of Biological Sciences, CT.C., Islamic Azad University, Tehran, Iran Maryam Peyvandi Department of Biology, Faculty of Biological Sciences, NT.C., Islamic Azad University, Tehran, Iran Journal Article 2025 03 31 The combined effects of mycorrhizal fungi and Azotobacter bacteria alongside NPK fertilizer on growth, yield, essential oil quality, and antimicrobial properties of Foeniculum vulgare (fennel) were evaluated. Seed inoculation with biofertilizers and chemical fertilizer applications under controlled greenhouse conditions significantly enhanced plant height (112.5±2.9 cm), umbels per plant (39±3.6), thousand-seed weight (3.95±0.21 g), biological yield (4245±230 kg/ha), seed yield (1544±228 kg/ha), and harvest index (36.3±3.3%) compared to the control (p < 0.01). Essential oils extracted from treated plants demonstrated improved antimicrobial efficacy, with minimum inhibitory concentrations (MIC) against Aspergillus niger reduced by 50% to 62.5 μg/mL. Similar reductions in MIC values were observed for Penicillium digitatum, Escherichia coli, and Staphylococcus aureus. Minimum fungicidal and bactericidal concentrations (MFC/MBC) also decreased substantially with combined treatments. Results confirm that integrating biofertilizers enhances fennel growth, yield, and the antimicrobial potency of its essential oil, providing a sustainable alternative to chemical fertilizers in medicinal plant cultivation.