黄栌枯萎病菌拮抗细菌的分离与鉴定

Isolation and identification of an antagonistic bacterium against smoke tree wilt fungus Verticillium dahliae

为了获得能有效拮抗黄栌枯萎病的大丽轮枝菌(Verticillium dahliae)和尖孢镰刀菌(Fusarium oxysporum)的生防菌株,采用系列稀释分离法和平板对峙法从盐碱地土壤中筛选拮抗细菌,基于形态特征、生理生化特性和16S rDNA序列分析鉴定菌株,并测定其无菌滤液和挥发性气体的抑菌活性。筛选结果表明,菌株C-2-3-2是一株能有效抑制黄栌枯萎病菌和尖孢镰刀菌的生防菌株,经鉴定其为枯草芽孢杆菌(Bacillus subtilis)。该菌株的无菌滤液对黄栌枯萎病菌和尖孢镰刀菌均具有明显的体外抑菌作用,且能有效抑制黄栌枯萎病菌微菌核的形成。同时,其挥发性气体也能有效抑制黄栌枯萎病菌的生长。另外,研究还发现该菌株能产生铁载体和合成氨,并产生几丁质酶、纤维素酶、蛋白酶和β-1,3-葡聚糖酶。研究结果表明菌株C-2-3-2在黄栌枯萎病生物防治中具有较好的应用潜力和较高的研究价值。

In order to isolate and characterize an antagonistic bacterial strain againstVerticillium dahliaeandFusarium oxysporum, serial dilution and plate-confrontation methods were used for preliminary screening and selecting antagonisticbacteria from saline-alkali soil. Strain identification was based on morphological and physiological characteristics, andphylogenetic analysis of 16 S rDNA sequence. The antagonistic effects of sterile culture filtrates and volatiles of antagonis-tic bacteria were determined. An antagonistic bacteria, named as C-2-3-2, was isolated and identified asBacillus subtilis. The results indicated that sterile culture filtrate of the strain exhibited obviousin vitroinhibition againstV. dahliae andF. oxysporum, and suppressed the production of microsclerotia ofV. dahliae. The volatiles also effectively inhibitedthe mycelial growth ofV. dahliae. In addition, the results indicated that C-2-3-2 could produce ammonia and sid-erophore, and also could produce cell wall degrading enzymes, such as chitinase, cellulose, protease and β-1,3-glu-canase. It indicted that strain C-2-3-2 had high research value and potentials for biological control ofVerticilliumwiltofCotinus coggygria.