广西北部湾入侵植物互花米草内生可培养细菌多样性及促生防病活性分析

【目的】探究不同入侵程度互花米草（Spartina alterniflora）根、茎和叶内生可培养细菌的多样性，并分析其对植物的防病促生活性，为互花米草入侵研究提供新思路，同时为后续的农业应用提供菌种资源。【方法】以不同入侵程度的互花米草为研究对象，采用6种选择培养基，通过稀释涂布法分离内生细菌；利用16S rRNA序列相似性及构建系统发育进化树确定内生细菌的分类地位。通过平板对峙法检测内生细菌拮抗香蕉枯萎病病原菌活性；通过功能培养基分析内生细菌产吲哚乙酸（IAA）、溶磷和固氮等促生活性。【结果】从互花米草的根、茎和叶中共分离出269株内生细菌，根据菌落形态和培养特征去重复后获得82株细菌；对内生细菌进行16S rRNA测序及比对分析，82株细菌分属于6纲16目19科31属，其中包括固氮细菌21株（占25.61%）、产IAA细菌21株（占25.61%）、溶磷菌11株（占13.41%），可拮抗香蕉枯萎病病原菌14株（占17.07%），并发现潜在新种13株（占15.85%）。互花米草入侵程度不同，内生细菌多样性也发生变化，随着入侵程度的增加，γ变形菌占据优势，而放线菌和芽孢杆菌多样性增加。【结论】互花米草内生细菌具有丰富的多样性，且多具有促生活性和生防功能，在未来农业生产中具有潜在应用价值。

Diversity of culturable endophytic bacteria in invasive plant Spartina alterniflora of Guangxi Beibu Gulf and their biocontrol effect and plant-growth-promoting activity

【Objective】To study diversity of culturable endophytic bacteria in the roots, stems and leaves in different degrees of invasion of Spartina alterniflora, and analyze their biocontrol and plant-growth-promoting activity, provide new research ideas for S. alterniflora invasion research and provide microbial resources for subsequent agricultural applications.【Method】S. alterniflora with different invasion degrees were used as the research object, and six selective media were used to isolate microorganisms by dilution coating method. 16S rRNA sequence similarity and construction of phylogenetic trees were used to determine the classification status of microorganisms. The plate confrontation method was used to detect the antagonistic activity of the bacterial strain against the pathogen of banana fusarium wilt;and the indole acetic acid production(IAA), phosphorus solubilization and nitrogen fixation were analyzed through functional plate analysis.【Result】A total of 269 endophytic bacteria were screened from the roots, stems and leaves of S. alterniflora. After deduplication according to the colony morphology and culture characteristics, the 16S rRNA sequencing and comparison of 82 strains were performed, and they belonged to 6 classes, 16 orders, 19 families and 31 genera, including 21 strains of nitrogen-fixing bacteria(25.61%), 22 strains of IAA-producing bacteria(25.61%), 11 strains of phosphate solubilizing bacteria(13.41%), 14 strains(17.07%) could antagonize the pathogen of banana fusarium wilt, and discovered potential 13 new strain species(15.85%). The degree of invasion of S. alterniflora was different, and the diversity of endophytic bacteria also changed. As the degree of invasion increased, γ-proteobacteria dominated, while the diversity of actinomycetes and bacillus increased.【Conclusion】The endophytes of S. alterniflora are rich in diversity, and mostly have life-promoting and biological control functions. They have potential application value in future agricultural production.