Fontana Riccardo, Macchi Giovanna, Caproni Anna, Sicurella Mariaconcetta, Buratto Mattia, Salvatori Francesca, Pappadà Mariangela, Manfredini Stefano, Baldisserotto Anna, Marconi Peggy
Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, 44121 Ferrara, Italy.
Department of Life Sciences and Biotechnology, University of Ferrara, 44121 Ferrara, Italy.
Plants (Basel). 2022 Mar 31;11(7):957. doi: 10.3390/plants11070957.
(EA) is a phytopathogenic bacterium, the causative agent of bacterial fire blight, a disease that affects Rosaceaes. In order to replace antibiotics and copper, the antimicrobial activity of three extracts of Lam., methanolic (MeOH-MOE), hydroalcoholic (HA-MOE) and hydroalcoholic with maltodextrins (HAMD-MOE), was tested on eleven strains of EA isolated from apple trees by the Emilia-Romagna Phytosanitary Department. MIC and MBC have been evaluated; biofilm formation, swarming motility and amylovoran production were performed with the crystalviolet, soft-agar assay and the amylovoran method. All extracts demonstrated bacteriostatic activity at a concentration of 1 mg/mL, resulting in a 80% reduction in biofilm formation. HAMD-MOE, MeOH-MOE and HA-MOE caused an inhibition of motility of 60%, 65% and 30% after 6 days and a decrease in amylovoran synthesis of 84%, 63% and 93%, respectively. In planta results showed how the compounds were able to inhibit EA virulence on apple trees, mainly if they were applied as a preventive treatment, although the treatment showed a significant reduction in fire blight symptoms progression. The antibacterial activity of the extracts is mainly due to the high concentration of polyphenolic compounds detected in the extracts that was able to alter the permeability of bacterial membrane, resulting in slowing the synthesis of ATP and consequently of all ATP-dependent functions, such as motility and less selectivity towards harmful compounds, which can, thus, enter the cytoplasm and inhibit enzymes involved in replication and quorum sensing. The efficacy, eco-compatibility and low cost make such extracts a potential tool for the control of bacterial fire blight.
欧文氏菌（EA）是一种植物致病细菌，是细菌性火疫病的病原体，这种疾病会影响蔷薇科植物。为了替代抗生素和铜制剂，艾米利亚 - 罗马涅植物保护部门对从苹果树上分离出的11株EA菌株测试了三种提取物（唇形科植物提取物，甲醇提取物（MeOH - MOE）、水醇提取物（HA - MOE）和含麦芽糖糊精的水醇提取物（HAMD - MOE））的抗菌活性。评估了最低抑菌浓度（MIC）和最低杀菌浓度（MBC）；通过结晶紫法、软琼脂试验和支链淀粉测定法进行生物膜形成、群体运动性和支链淀粉产生的检测。所有提取物在浓度为1mg/mL时均表现出抑菌活性，导致生物膜形成减少80%。6天后，HAMD - MOE、MeOH - MOE和HA - MOE分别导致60%、65%和30%的运动性抑制，支链淀粉合成分别减少84%、63%和93%。植物体内实验结果表明，这些化合物能够抑制EA对苹果树的毒力，尤其是在作为预防性处理应用时，尽管该处理显示火疫病症状进展显著减轻。提取物的抗菌活性主要归因于提取物中检测到的高浓度多酚化合物，这些化合物能够改变细菌膜的通透性，导致ATP合成减慢，进而所有依赖ATP的功能减慢，如运动性以及对有害化合物的选择性降低，从而使这些有害化合物能够进入细胞质并抑制参与复制和群体感应的酶。这些提取物的有效性、生态兼容性和低成本使其成为控制细菌性火疫病的潜在工具。
