Abstract：
Biocontrol of phytopathogens involving the use of bioactive compounds produced by lactic acid bacteria (LAB), is a promising approach to manage many diseases in agriculture. In this study, a lactic acid bacterium designated YB1 was isolated from fermented olives and selected for its antagonistic activity against Verticillium dahliae (V. dahliae) and Agrobacterium tumefaciens (A. tumefaciens). Based on the 16S rRNA gene nucleotide sequence analysis (1565 pb, accession number: OR714267), the new isolate YB1 bacterium was assigned as Leuconostoc mesenteroides YB1 (OR714267) strain. This bacterium produces an active peptide \"bacteriocin\" called BacYB1, which was purified in four steps. Matrix-assisted lasers desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS) based approach was performed to identify and characterize BacYB1. The exact mass was 5470.75 Da, and the analysis of the N-terminal sequence (VTRASGASTPPGTASPFKTL) of BacYB1 revealed no significant similarity to currently available antimicrobial peptides. The BacYB1 displayed a bactericidal mode of action against A. tumefaciens. The potentiel role of BacYB1 to supress the growth of A. tumefaciens was confirmed by live-dead cells viability assay. In pot experiments, the biocontrol efficacy of BacYB1 against V. dahliae wilt on young olive trees was studied. The percentage of dead plants (PDP) and the final mean symptomes severity (FMS) of plants articifialy infected by V. dahliae and treated with the pre-purified peptide BacYB1 (preventive and curative treatments) were significantly inferior to untreated plants. Biochemical analysis of leaves of the plants has shown that polyophenols contents were highly detected in plants infected by V. dahliae and the highest contents of chlorophyl a, b and total chlorophyll were recorded in plants treated with the combination of BacYB1 with the biofertilisant Humivital. BacYB1 presents a promising alternative for the control of Verticillium wilt and crown gall diseases.
摘要：
涉及使用乳酸菌（LAB）产生的生物活性化合物的植物病原体的生物防治，是管理农业中许多疾病的一种有前途的方法。在这项研究中,从发酵橄榄中分离出一种名为YB1的乳酸菌，并选择了其对黄萎病菌的拮抗活性（V。大丽花）和根癌农杆菌（A.tumefaciens)。基于16SrRNA基因核苷酸序列分析(1565pb，登录号:OR714267),新分离出的YB1细菌被指定为中肠明串珠菌YB1（OR714267）菌株。这种细菌产生一种称为BacYB1的活性肽“细菌素”，该肽分四个步骤纯化。进行基于基质辅助激光解吸/电离（MALDI）飞行时间（TOF）质谱（MS）的方法来识别和表征BacYB1。精确质量为5470.75Da,对BacYB1的N端序列（VTRASGASTPPGTASPFKTL）的分析显示与目前可用的抗菌肽没有显着相似性。BacYB1显示了对根癌农杆菌的杀菌作用模式。BacYB1抑制根癌农杆菌生长的潜在作用通过活死细胞活力测定得到证实。在盆栽实验中,研究了BacYB1对幼龄橄榄树上大丽花枯萎病的生物防治效果。被大丽花人工感染并用预纯化肽BacYB1（预防性和治愈性处理）处理的植物的死亡植物百分比（PDP）和最终平均症状严重程度（FMS）明显低于未处理的植物。植物叶片的生化分析表明，在受大丽花弧菌感染的植物中，多酚类含量高，叶绿素a含量最高，在用BacYB1与生物肥料Humivital的组合处理的植物中记录b和总叶绿素。BacYB1为控制黄萎病和冠gall病提供了有希望的替代方法。
