玉米拮抗内生细菌资源的筛选及鉴定

Screening and biological function determination of excellent antagonistic endophytic bacteria in maize

摘要:

【目的】 开发和利用玉米内生细菌资源。【方法】 从玉米穗、叶片、茎部和鞘部分离内生细菌， 采用对峙培养法筛选优良拮抗内生细菌，测定优良拮抗内生细菌的抑菌谱、产IAA、溶磷、固氮和产铁载体等生物功能，并根据形态特征和分子生物学方法进行鉴定。【结果】 从玉米中共分离得到128株内生细菌，其中从鞘部分离得到的内生细菌ZY-Q-26对拟轮枝镰孢菌（Fusarium sporotrichioides）、变红镰孢菌（F. incarnatum）、尖刀镰孢菌（F. oxvsporum）和层出镰孢菌（F. proliferatum）具有抑制作用， 其抑菌率分别为68.66%、68.74%、63.89%和65.84%，且其具有产IAA和固氮能力。ZY-Q-26为革兰氏阳性菌（G+），菌体杆状，大小为0.321~0.652 μm×0.053 ~0.086 μm。通过形态学观察和16S rDNA及gyrA基因序列同源性分析，将其鉴定为枯草芽孢杆菌（Bacillus subtilis）。【结论】 从玉米鞘部分离出的优良拮抗细菌ZY-Q-26鉴定为枯草芽孢杆菌。该研究结果为玉米内生细菌资源的开发和利用奠定基础，也为玉米病害的生物防治提供菌种资源。

Abstract:

【Objective】 In order to explore and utilize the endophytic bacteria resources in maize，endophytic bacteria were isolated from the leaf sheath of maize in this experiment.【Method】The antagonistic endophytic bacteria were screened using confrontation culture method，and the antibacterial spectrum，IAA production，phosphate solubilization，nitrogen fixation and siderophore production of excellent antagonistic endophytic bacteria were further determined.【Result】 The results showed that 35 endophytic bacteria were isolated from the sheath of maize. Among them，the inhibitory rates of endophytic bacteria ZY-Q-26 against Fusarium sporotrichioides，F. incarnatum，F. oxvsporum and F. proliferatum were 68. 66%，68. 74%，63. 89% and 65. 84%，respectively. The detection showed that medium could produce IAA and nitrogen fixation. ZY-Q-26 was a Gram-positive （G+） bacterium，with a rod- shaped and a size of 0. 321~0. 652 μm× 0.053~0. 086 μm. Combining with the morphological characteristics and 16S rDNA and gyrA gene sequence homology analysis，this strain was identified as Bacillus subtilis.【Conclusion】 The excellent antagonistic bacterium ZY-Q-26 isolated from the sheath of maize was identified as Bacillus subtilis. The results of this study laid a foundation for the exploration and utilization of endophytic bacterial resources in maize， and provided endophytic bacteria resources for the biological control of maize melasma.