苎麻促生菌的筛选、鉴定及其促生效应

【目的】以苎麻(Boehmeria nivea L. Gaud)根及根围土壤为研究材料，进行苎麻促生菌的筛选，并初步探索其促生作用机制。【方法】首先，以溶磷和解钾为基本筛选标准，初筛菌株在实验室条件下测定多项促生能力进行复筛；然后通过种子萌发、盆栽试验测定菌株对苎麻的促生效应，最后，通过形态观察、生理生化特性和16S rRNA基因序列同源性分析，对促生菌株进行分类学鉴定。【结果】从苎麻根和根围土壤中分离得到了13株菌同时具备溶磷和解钾能力，其中4株菌(RA-2、RAM-2、RAM-5和RAM-6)具备产铁载体、产IAA和产氨能力。种子萌发和盆栽试验的测定结果显示：4株菌株均能促进苎麻种子的萌发和植株的生长，其中菌株RA-2和RAM-5相比于对照处理能显著提高苎麻种子的萌发率、幼根长、株高和根系干重。分类鉴定结果显示菌株RA-2和RAM-5均属于伯克霍德菌属(Burkholderia)。【结论】从苎麻根围筛选到具有促生能力的菌株，为进一步开发研制苎麻专型促生菌剂或专型微生物有机肥提供资源。

Isolation and identification of plant growth-promoting bacteria (PGPB) from ramie (Boehmeria nivea L. Gaud) rhizosphere and their promoting growth effects

Objective] We used roots and rhizosphere soils of ramie (Boehmeria nivea L. Gaud) to isolate plant growth promoting bacteria (PGPB), and then studied the mechanism why they promote growth of ramie in preliminarily. Methods] Preliminary screening of PGPBs under the premises of bacteria have the abilities of phosphate-and potassium-solubilizing, moreover, the bacteria strains were screened by testing their abilities of siderophore, indole acetic acid (IAA) and ammonia production in vitro. Then, seeds germination and pot experiments were conducted to measure the promoting-growth effects on ramie of the isolates. Finally, PGPBs were classified and identified by combining physiological and biochemical tests and 16S rRNA gene sequences analysis. Results] Thirteen strains were isolated based on the abilities of phosphate- and potassium-solubilizing, of which four strains (RA-2, RAM-2, RAM-5, and RAM-6) also exhibited plant growth promoting properties like siderophores, IAA and ammonia production. Seeds germination and pot experiments showed that four selected strains could promote growth of ramie, moreover, strain RA-2 and RAM-5 could significantly improve the germination rates, root lengths, plant heights, and root dry weights, both of isolates RA-2 and RAM-5 were identified as Burkholderia sp.. Conclusion] PGPBs which were isolated from ramie rhizosphere will helpful for developing the specially PGPB microbial inoculants or bio-organic fertilizers of ramie.