玉米大斑病生防细菌的筛选、鉴定及其抑制作用

为了找到对玉米大斑病有较好防治效果的细菌菌株，采用平板对峙法和管碟法2 种筛选方法分离筛选多个地方采集的玉米叶片上细菌菌株，生理生化学和分子生物学法对细菌菌株进行鉴定，最后通过采用菌株发酵滤液对病原菌菌丝和孢子萌发进行处理的方法，研究拮抗菌株的抑菌作用。结果表明，从分离到267 株细菌菌株中，筛选到1 株对玉米大斑病有较好抑制作用的细菌菌株SCG-02，经鉴定为洋葱伯克霍尔德氏菌(Burkholderia cepacia)，不同浓度的菌株SCG-02 发酵滤液可不同程度的抑制病原菌菌丝生长和孢子萌发，处理后的病原菌菌丝由丝状变成串珠状，当发酵滤液浓度是60%时，孢子完全不萌发，且产生泡囊状结构。通过试验研究表明，从玉米叶片上分离筛选得到的细菌菌株SCG-02 对玉米大斑病有较好的防治作用。

Isolation, Identification and Antagonistic Activity of Biocontrol Bacterium Against Northern Corn Leaf Blight

To identify strains of bacteria with strong antagonistic activities to Exserohilum turcicum, plate confrontation and tube plate methods were used to select the bacterium strains isolated from the corn leaves collected from various sites. The bacterium strains were identified based on their morphological, physiological, biochemical and molecular characteristics. Fermentation filtrate from this bacterium was then used to investigate the effect on pathogen mycelial growth and spore germination. The result showed that one bacterium strain, SCG- 02, was selected from two hundred and sixty- seven bacterium strains, which showed strong antagonistic activities to E. turcicum. This strain of bacterium was then identified as Burkholderia cepacia. Different concentrations of SCG-02 fermentation filtrate showed different degrees of inhibition for the pathogen mycelial growth and spore germination in the antagonism experiment. The mycelium of E. turcicum turned to be moniliform after SCG-02 fermentation filtrate treatment and the strongest inhibiting effect was observed at the concentration of 60%, at which the spores cannot germinate completely and bubbles cystic structure was produced at the end of spore germinal tubes. In conclusion, this selected bacteria strain, SCG-02, displayed strong antagonistic activities to E. turcicum, which indicated a positive potential in the application of E. turcicum control.