落地生根内生固氮菌多样性和促生特性

【背景】内生固氮菌可以定殖于植物体内为植物提供营养物质,还能通过代谢促进植物生长,目前对于落地生根内生菌的研究鲜见报道。【目的】研究落地生根中内生固氮菌多样性。【方法】从表面消毒的植物组织中分离纯化内生菌,并通过乙炔还原法测定菌株的固氮酶活性。采用SDS-PAGE全细胞蛋白电泳和IS指纹图谱对菌株聚类,各类群代表菌株进行16S rRNA基因系统发育分析和生理生化鉴定。测定菌株固氮、分泌生长素和ACC脱氨酶、产铁载体、溶磷和解钾等促生特性。【结果】从落地生根中分离纯化出26株内生固氮菌,聚为5个类群,隶属于4个属的5个菌种,且各类群代表菌株具有多种促生功能。【结论】从落地生根中分离获得的内生菌具有丰富的遗传多样性和促生特性,并且存在新的微生物资源,有待开发利用。

Diversity and growth promotion of endophytic diazotrophic bacteria isolated from Bryophyllum pinnatum

Background] Endophytic diazotrophic bacteria can colonize within plants to provide nutrients for plants and promote plant growth through metabolism. Objective] We studied the diversity of endophytic diazotrophic bacteria isolated from Bryophyllum pinnatum. Methods] Endophytes were isolated and purified from surface sterilized plant tissues. Nitrogen-fixation ability of the isolates was tested by acetylene reduction assay. SDS-PAGE patterns of the whole-cell protein electrophoresis and IS-PCR DNA finger-printings were used to group these isolates. The representative strains were identified by physiological and biochemical characteristics, and the 16S rRNA gene sequence analysis. The growth promotion of nitrogen fixation, secretion of auxin and ACC deaminase, siderophore production, solubilizing phosphorus and potassium were determined. Results] A total of 26 endophytic diazotrophic bacteria were isolated from Bryophyllum pinnatum and classified into 5 groups, belonging to 5 species of 4 genera. All representative strains had various plant growth promoting activity. Conclusion] Endophytes isolated from Bryophyllum pinnatum have abundant genetic diversity and growth promoting characteristics.