芽孢杆菌拮抗苹果树腐烂病菌的筛选、鉴定及抑菌活性初探

【背景】苹果树腐烂病发生面积广、危害严重，目前对于该病的防治以化学防治为主，但存在一定的弊端，因此迫切需要寻找一种对该病高效、安全的防治措施。【目的】从敦煌地区盐碱土壤中筛选出对苹果树腐烂病有良好抑制作用的芽孢杆菌菌株。【方法】采用平板对峙培养法和菌丝生长速率法对盐碱土中分离筛选的芽孢杆菌进行拮抗苹果树腐烂病菌的筛选，并对优良拮抗效果菌株进行离体组织防效测定、发酵培养基选择以及结合培养形态、生理生化及16S rRNA基因序列分析进行菌种鉴定。【结果】初筛阶段菌株7-2-1-2对病原菌的抑制率为86.18%，复筛试验中发酵液对病原菌的抑制率为73.2%；在离体枝条创面涂抹菌株7-2-1-2发酵原液后，苹果树腐烂病菌的生长可被完全抑制；菌株7-2-1-2的最优生长培养基为NBY培养基；经初步鉴定，菌株7-2-1-2为枯草芽孢杆菌亚种(Bacillus subtilis subsp. spizizenii)。【结论】菌株7-2-1-2对苹果树腐烂病有较好的生防效果，为该病生防菌剂的选择提供了必要的菌种资源。

Screening, identification and preliminary study on biocontrol effect of antagonistic Bacillus against the pathogen of Valsa mali for apple tree

Background] Apple tree canker is widespread and dangerous. Currently, chemical control is the main way to prevent and cure it. However, there are some drawbacks. Therefore, it is urgent to find an effective and safe prevention and control measure. Objective] In order to select Bacillus isolated in Saline-alkali soil from Dunhuang that showed significantly antagonistic effect on the Valsa mali growth. Methods] The antifungal activities of selected Bacillus were investigated by dual culture assar and colony diameter assay, respectively. In addition, the control effect of antagonistic bacteria strains against Valsa mali in detached apple twigs in vitro and selection for medium were determined and the antagonistic Bacillus was identified based on morphological, physiological and biochemical characteristics and 16S rRNA gene phylogenetic analysis. Results] The results revealed that strain 7-2-1-2 exhibited a strong antagonistic activity against V. mali, inhibiting significantly the germination of conidia and the growth of hyphae and especially the inhibitory rate of strain 7-2-1-2 was 86.18% and 73.2% in second screening. Strain 7-2-1-2 fermentation broth applied prior to wound inoculation of apple twigs with V. mali resulted in total inhibition of infection. The optimum growth medium of strain 7-2-1-2 was NBY. Strain 7-2-1-2 was identified as Bacillus subtilis subsp. spizizenii. Conclusion] These results indicated that the strain 7-2-1-2 promised to provide a new biological control method in containing apple canker.