Jung Myunghee, Bang Seon-Woo, Lee Ji-Eun, Kim Jeong-Eun, Park Il-Kwon
Bioinformatics Group, R&D Center, Insilicogen, Inc., Yongin-si, Gyeonggi-do 16954, Republic of Korea.
Department of Agriculture, Forestry and Bioresources, College of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Republic of Korea.
Pestic Biochem Physiol. 2025 Nov;214:106601. doi: 10.1016/j.pestbp.2025.106601. Epub 2025 Jul 25.
In this study, we evaluated the antibacterial activities of plant essential oils (EOs) from the Lamiaceae family against Agrobacterium tumefaciens to find new eco-friendly antimicrobials. Thymus vulgaris L. (thyme white) EO demonstrated the most potent fumigant antibacterial activity among these. Key compounds identified in thyme white EO, including thymol, carvacrol, S-(-)-α-pinene, R-(+)-α-pinene, and (-)-limonene, also exhibited strong fumigant antibacterial activity against A. tumefaciens. The inhibition zone diameters observed for thymol, carvacrol, R-(+)-α-pinene, S-(-)-α-pinene, thyme white EO, and S-(-)-limonene were 2.85, 2.74, 1.64, 1.55, 1.15, and 0.86 cm, respectively, at a concentration of 5 mg per paper disc. Only thyme white EO, thymol, and carvacrol exhibited contact antibacterial activity against A. tumefaciens. The minimum inhibition concentrations (MIC) of thyme white EO, thymol, carvacrol, and streptomycin were 800 μg/mL, 350 μg/mL, 350 μg/mL, and 3.125 μg/mL, respectively. Using confocal laser scanning microscopy, we observed intracellular reactive oxygen species (ROS) production and membrane damage in A. tumefaciens treated with thyme white EO, thymol, and carvacrol. Additionally, we analyzed the differential gene expression level in A. tumefaciens treated with thyme white EO, thymol, and carvacrol, comparing them to untreated cells to elucidate the mode of action. In particular, the expression of manganese transport-related genes (sitABCD and mntH) was significantly downregulated, which impaired the function of sod. As a result, the system responsible for detoxifying ROS was disrupted. This led to excessive accumulation of ROS, causing damage to the cell membrane.
在本研究中，我们评估了唇形科植物精油对根癌土壤杆菌的抗菌活性，以寻找新型环保抗菌剂。百里香（Thymus vulgaris L.，白百里香）精油在这些精油中表现出最强的熏蒸抗菌活性。在白百里香精油中鉴定出的关键化合物，包括百里香酚、香芹酚、S-(-)-α-蒎烯、R-(+)-α-蒎烯和(-)-柠檬烯，对根癌土壤杆菌也表现出较强的熏蒸抗菌活性。在每片滤纸片含5 mg浓度下，观察到百里香酚、香芹酚、R-(+)-α-蒎烯、S-(-)-α-蒎烯、白百里香精油和S-(-)-柠檬烯的抑菌圈直径分别为2.85、2.74、1.64、1.55、1.15和0.86 cm。只有白百里香精油、百里香酚和香芹酚对根癌土壤杆菌表现出接触抗菌活性。白百里香精油、百里香酚、香芹酚和链霉素的最低抑菌浓度（MIC）分别为800 μg/mL、350 μg/mL、350 μg/mL和3.125 μg/mL。使用共聚焦激光扫描显微镜，我们观察到用白百里香精油、百里香酚和香芹酚处理的根癌土壤杆菌细胞内活性氧（ROS）的产生和膜损伤。此外，我们分析了用白百里香精油、百里香酚和香芹酚处理的根癌土壤杆菌与未处理细胞相比的差异基因表达水平，以阐明其作用模式。特别是，锰转运相关基因（sitABCD和mntH）的表达显著下调，这损害了超氧化物歧化酶（sod）的功能。结果，负责ROS解毒的系统被破坏。这导致ROS过度积累，对细胞膜造成损伤。
