一株拮抗真菌的蛇足石杉内生细菌分离鉴定及培养条件优化

Isolation and Identification of Endophytic Bacteria H-6 with High Antifungal Activity from Huperzia serrata

从蛇足石杉(Huperzia serrata)叶片中分离到一株对小麦赤霉(Fusarium graminearum)等多种植物病原真菌有强拮抗作用的内生细菌H-6。通过形态和培养特性观察、生理生化实验及16SrDNA序列分析,初步鉴定该菌属于伯克霍尔德属,命名为Burkholderia sp.H-6。同时还对该菌培养条件进行了优化,得出马铃薯浸出液中添加2.5%的甘露醇和0.1%NaNO3有利于细胞生长和抑菌活性的产生,最适培养温度为28℃,最佳初始pH4.0。

In this study, nearly 200 endophytic bacteria were isolated from different part of Huperzia serrata, over 60 bacterium with clear antifungal activity were selected from those cultures. Among them, strain H-6 exhibited the highest antifungal activity which was strongly inhibits the growth of many plant pathogenic fungi such as Sclerotinia scleroliorum, Fusarium graminearumt, Sclerotinia libertiana, Phytophthora capsici Leonia and Sesame fusarium wilt. According to the characteristics of morphology, physiology and biochemistry tests and the comparison of 16S rDNA sequence, the strain H-6 was similar to the Burkholderia. So strain H-6 was identified as Burkholderia sp. H-6. The results also showed that Burkholderia sp. H-6 was markedly different from Burkholderia cepacia that was applied widely in agriculture as antagonistic bacteria. The medium and culture conditions of the strain all were optimized by single factor and orthogonal experiments. In the investigation of the culture condition, growth was carried out in a basal medium （potato juice） and gradually supplemented with the various ingredients to be investigated. The major ingredients being investigated included carbon sources and nitrogen sources. The optimal antifungal activity production condition is growth in a medium （potato juice with 2.5% mannitol and 0.1% NaNO3）, initial pH 4.0 at 28℃.