解淀粉芽孢杆菌X60对烟草叶际微生物拮抗活性及叶际微生态的影响

Antagonistic activity of Bacillus amyloliquefaciens X60 against tobacco phyllosphere microorganisms and its impact on phyllosphere microbial community structure

摘要:

目的 为研究解淀粉芽孢杆菌X60对烟草叶际微生物的拮抗活性，以及施用X60菌剂后对叶际微生物菌群的影响。方法 采用生物活性测定法评价其对叶际20种致病真菌、15种非致病真菌、2种致病细菌及15种非致病细菌的拮抗活性，利用扩增子测序技术解析施用该菌剂对烟草叶际微生物菌群结构的影响。结果 解淀粉芽孢杆菌X60对米根霉等13种致病真菌及哈茨木霉等12种非致病真菌的拮抗活性强，抑制率为60.00%-80.00%；对细极链格孢等7种致病真菌及小孢梭孢壳等3种非致病真菌的拮抗活性较弱(10.00%-59.00%)；对丁香假单胞烟草致病变种、丁香假单胞杆菌角斑专化型2种致病细菌及微小杆菌等7种非致病细菌的抑菌圈直径均大于20 mm。X60菌剂田间施用后对叶斑病的防治效果为52.35%，感病组织中优势细菌泛菌的相对丰度升高，细菌多样性和丰富度先下降后上升；真菌丰富度下降，多样性先下降后上升，植物病原菌类群相对丰度由44.87%降至6.71%。结论 解淀粉芽孢杆菌X60抗菌谱广，对烟草叶际的25种真菌及9种细菌具有强拮抗活性，对烟草叶斑病的田间防治效果为52.35%，施用后能有效降低叶际植物病原菌的丰度，该菌剂具有防控烟草叶斑病的应用潜力。

Abstract:

Objective To investigate the antagonistic activity of Bacillus amyloliquefaciens X60 against tobacco phyllosphere microorganisms and its effects on the phyllosphere microbial community of tobacco.Methods Bioactivity assays were conducted to evaluate the antagonistic effects of B. amyloliquefaciens X60 against 20 species of pathogenic fungi, 15 species of non-pathogenic fungi, 2 specialized forms of pathogenic bacteria, and 15 species of non-pathogenic bacteria. Amplicon sequencing was employed to assess the influence of this strain on the phyllosphere microbial community structure.Results B. amyloliquefaciens X60 exhibited strong antagonistic activity (inhibition rates of 60.00%-80.00%) against 13 species of pathogenic fungi (e.g., Rhizopus oryzae) and 12 species of non-pathogenic fungi (e.g., Trichoderma harzianum). Moderate antagonism (inhibition rates of 10.00%-59.00%) was observed against 7 species of pathogenic fungi (e.g., Alternaria tenuissima) and 3 species of non-pathogenic fungi (e.g., Thielavia microspora). Significant antibacterial activity (inhibition zone diameter >20 mm) was detected against 2 specialized forms of pathogenic bacteria (Pseudomonas syringae pv. tabaci and pv. angulata) and 7 non-pathogenic bacteria (e.g., Exiguobacterium). After application, X60 showed the control efficacy of 52.35% against tobacco leaf spot. Following treatment, the relative abundance of Pantoea—a genus of opportunistic bacteria dominating the infected tissue—increased, whereas bacterial diversity and richness initially declined and then recovered. Fungal richness decreased throughout the observation period, while fungal diversity exhibited a transient decrease followed by a rebound. The relative abundance of phytopathogenic fungi declined from 44.87% to 6.71%.Conclusion B. amyloliquefaciens X60 possesses a broad antimicrobial spectrum and exerts strong antagonistic activity against 25 fungal and 9 bacterial species colonizing the tobacco phyllosphere. Under field conditions, the strain provided 52.35% control of tobacco leaf spot and significantly reduced the abundance of foliar phytopathogens, demonstrating the potential as a biocontrol agent for the management of this disease.