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通过组织分离法,在不同健康果树的木质部中分离到235株内生细菌。通过平板对峙法对所得菌株进行了初筛和复筛,得到6株拮抗作用较强的菌株。用过滤和高温灭菌得到的菌株发酵液进行抑菌谱试验,最终获得拮抗作用较强的内生细菌X8。对X8菌株在植物体内定殖、分类鉴定和防治作用的深入研究。结果表明:X8菌株可以在杏、辣椒等植物中定殖。X8菌株发酵液对辣椒疫霉病菌(Phytophthora capsici)抑制作用最强,达80.3%,对3种链格孢菌(Alternaria)病原菌的抑制作用达到75%以上,对番茄灰霉病和辣椒疫病的防效达到75.4%和79.3%,显著高于50%腐霉利和25%甲霜灵的防效。经16S rDNA序列分析,X8菌株与枯草芽孢杆菌Bacillus subtilis的16S rDNA序列的同源性达99%。综合形态特征、生理生化特性,最终将X8鉴定为B.subtilis,在GenBank中序列登录号为HQ647257。
Through tissue separation, 235 endophytic bacteria were isolated from the xylem of different healthy fruit trees. The obtained strains were preliminarily screened and re-screened by plate confrontation method, and six strains with strong antagonistic activity were obtained. Antibacterial spectrum test was carried out on the fermentation broth of the strain obtained by filtration and high-temperature sterilization to finally obtain the endophytic bacteria X8 with stronger antagonistic effect. In-depth study of the colonization, classification, identification and prevention of X8 strains in plants. The results showed that: X8 strains can be colonized in plants such as apricot and pepper. The fermentation broth of X8 strain had the strongest inhibitory effect on Phytophthora capsici (80.3%) and the inhibition of three pathogenic bacteria (Alternaria) to over 75% Control effect reached 75.4% and 79.3%, significantly higher than 50% of pythium Lee and 25% metalaxyl control effect. After 16S rDNA sequence analysis, the 16S rDNA sequence of X8 strain and Bacillus subtilis had 99% homology. Comprehensive morphological, physiological and biochemical characteristics, eventually identified as B. subtilis X8, in GenBank accession number HQ647257.