Red de Estudios Moleculares Avanzados, Instituto de Ecología, A.C. Carretera antigua a Coatepec 351, Col. El Haya, 91070 Xalapa, Veracruz, México.
Departamento de Ingeniería Genética, Centro de Investigación y de Estudios Avanzados. Km. 9.6 Lib. Nte. Carr. Irapuato-León. 036824 Irapuato, Guanajuato, México.
Microbiol Res. 2020 May;235:126440. doi: 10.1016/j.micres.2020.126440. Epub 2020 Feb 17.
Although the use of crop-associated bacteria as biological control agents of fungal diseases has gained increasing interest, the biotechnological potential of forest tree-associated microbes and their natural products has scarcely been investigated. The objective of this study was to identify bacteria or bacterial products with antagonistic activity against Fusarium solani and Fusarium kuroshium, causal agent of Fusarium dieback, by screening the rhizosphere and phyllosphere of three Lauraceae species. From 195 bacterial isolates, we identified 32 isolates that significantly reduced the growth of F. solani in vitro, which mostly belonged to bacterial taxa Bacillus, Pseudomonas and Actinobacteria. The antifungal activity of their volatile organic compounds (VOCs) was also evaluated. Bacterial strain Bacillus sp. CCeRi1-002, recovered from the rhizosphere of Aiouea effusa, showed the highest percentage of direct inhibition (62.5 %) of F. solani and produced diffusible compounds that significantly reduced its mycelial growth. HPLC-MS analyses on this strain allowed to tentatively identify bioactive compounds from three lipopeptide groups (iturin, surfactin and fengycin). Bacillus sp. CCeRi1-002 and another strain identified as Pseudomonas sp. significantly inhibited F. solani mycelial growth through the emission of VOCs. Chemical analysis of their volatile profiles indicated the likely presence of 2-nonanone, 2-undecanone, disulfide dimethyl and 1-butanol 3-methyl-, which had been previously reported with antifungal activity. In antagonism assays against F. kuroshium, Bacillus sp. CCeRi1-002 and its diffusible compounds exhibited significant antifungal activity and induced hyphal deformations. Our findings highlight the importance of considering bacteria associated with forest species and the need to include bacterial products in the search for potential antagonists of Fusarium dieback.
尽管利用作物相关细菌作为真菌病害的生物防治剂已经引起了越来越多的关注，但森林树木相关微生物及其天然产物的生物技术潜力几乎没有得到研究。本研究的目的是通过筛选三种樟科植物的根际和叶际，鉴定具有拮抗活性的细菌或细菌产物，以对抗尖孢镰刀菌和木贼镰刀菌，这两种菌是镰刀菌枯萎病的病原体。从 195 个细菌分离株中，我们鉴定出 32 个分离株在体外显著抑制了尖孢镰刀菌的生长，这些分离株主要属于芽孢杆菌、假单胞菌和放线菌等细菌分类群。还评估了它们挥发性有机化合物（VOCs）的抗真菌活性。从樟科植物的根际中回收的细菌菌株 Bacillus sp. CCeRi1-002 对 F. solani 的直接抑制率最高（62.5%），并产生了显著抑制其菌丝生长的可扩散化合物。对该菌株进行 HPLC-MS 分析，可初步鉴定出三个脂肽组（iturin、surfactin 和 fengycin）的生物活性化合物。Bacillus sp. CCeRi1-002 和另一种鉴定为假单胞菌的菌株通过排放 VOCs 显著抑制了 F. solani 菌丝的生长。对其挥发性图谱的化学分析表明，可能存在 2-壬酮、2-十一酮、二硫化二甲基和 3-甲基-1-丁醇，这些物质先前已被报道具有抗真菌活性。在对抗木贼镰刀菌的拮抗试验中，Bacillus sp. CCeRi1-002 及其可扩散化合物表现出显著的抗真菌活性，并诱导了菌丝变形。我们的研究结果强调了考虑与森林物种相关的细菌的重要性，以及在寻找镰刀菌枯萎病潜在拮抗剂时需要包括细菌产物。
