1株烟草赤星病拮抗芽孢杆菌的鉴定与活性研究

【目的】筛选对烟草赤星病具有拮抗作用的芽孢杆菌并进行鉴定，同时研究其抗菌作用。【方法】从陕西、云南、湖北和河南4省烟区采集烟草根际土壤和烟叶，从中分离筛选烟草赤星病拮抗芽孢杆菌，并对拮抗性最强的1株芽孢杆菌进行形态学、生理生化特性、16S rDNA序列鉴定及粗提物抑菌作用测定。【结果】从烟草表面及根际土壤分离得到的芽孢杆菌中有10株对烟草赤星病有拮抗效果，将其中效果最好的1株芽孢杆菌定名为M-07C2F，其抑菌条带宽度达14.2 mm；通过16S rDNA测序并结合其形态和生理生化特征，鉴定该菌株为解淀粉芽孢杆菌。通过显微观察发现，M-07C2F菌株使烟草赤星病病原真菌的菌丝生长出现畸形，菌丝体内部细胞原生质体分布不均匀，部分菌丝内原生质有流出形成空壳的现象。在离体条件下采用生长速率法，测得其对烟草赤星病菌丝生长有抑制作用，EC₅₀为12.82 mg/L；在活体条件下采用田间小区试验，测得当M-07C2F菌株粗提物质量浓度为80 mg/L时，其对烟草赤星病的防治效果达到86.0%。【结论】菌株M-07C2F对烟草赤星病菌的抑菌作用明显，该菌株通过抑制烟草赤星病菌菌丝生长、减少孢子萌发来抑制病菌对植株的侵染，且菌株粗提物质量浓度越高，抑菌能力越强。

Isolation,identification and antibacterial activity of antagonistic bacteria M-07C2F against Tobacco Brown Spot

【Objective】This research aims to screen out and identify the bacillus that shows an inhibitory effect on Tobacco Brown Spot,and examines this kind of effect closely.【Method】We collected the tobacco leaf and the rhizosphere soil from areas where mostly tobacco was grown in Shannxi,Yunnan,Hubei and Henan province.One strain of bacillus with the highest inhibitory effect was screened out.Then its morphology,physio-biochemical characteristics,the sequence of 16S rDNA and its crude extract’s inhibitory effect were all examined.【Result】There are ten strains of bacillus isolated from the skin of tobacco and the rhizosphere soil,exhibiting an inhibitory effect on Tobacco Brown Spot.The best of them is named M-07C2F,with the width of the inhibitory band up to 14.2 mm,and passes the sequencing of 16S rDNA.Considering its morphology and physio-biochemical characteristics,this strain of bacillus is identified to be Bacillus amyloliquefaciens.Observed through the microscope M-07C2F strain of Tobacco Brown Spot disease of mycelia growth of pathogenic fungi deformity,internal mycelium protiplasts are distributed unevenly,with some outflow of protoplasm formed with some outflow of protoplasm formed within the mycelium shell phenomenon.The growth rate methodology in vitro condition indicates that it has an inhibitory effect on the growth of hyphae of Tobacco Brown Spot,with EC50 being 12.82 mg/L,and the field plot research in living body shows that when the concentration of its crude extract reaches 80 mg/L,the control efficiency could be as high as 86.0%.【Conclusion】M-07C2F has an obvious inhibitory effect on Tobacco Brown Spot.It could prevent plants from being infected by inhibiting the spore germination and the growth of the hyphae of Tobacco Brown Spot.And the higher the concentration of its crude extract is,the better the inhibitory effect is.