高产吲哚乙酸及高泌氨巴西固氨螺菌的筛选与鉴定

目的：从玉米根际和土壤中分离具有高产吲哚乙酸较强的泌氨能力的巴西固氮螺菌。方法：分别通过半固体NFb培养基、CR培养基、LB培养基分离培养固氮菌株,并经过一系列菌落菌体形态特征、生理生化特性和16S rDNA序列测定等试验对其进行鉴定。结果：经分离纯化获得10株固氮菌,并鉴定均为巴西固氮螺菌（Azospirillum brasilense）,其中菌株R7在甘油半固体培养基上能分泌约14mmol/L的氨,在添加了色氨酸的培养基中能够合成58.8μg/ml的吲哚-3-乙酸（IAA）。结论：成功筛选得到一株既高产吲哚乙酸又有较强的泌氨能力的巴西固氮螺菌。

Isolation and Identification of Azospirillum brasilense Excreting High Concentration of IAA and Ammonium

Objective: To isolate Azospirillum yielding high concentration of IAA and ammonium from the maize rhizosphere and soil. Method: Strains of nitrogen-fixing bacteria were isolated on NFb semi-solid medium, CR medium, and LB medium. It was identified by a series of bacterial colony morphological, physiological characteristics and 16S rDNA sequences and other tests. Result: 10 strains of nitrogen-fixing bacteria were isolated and identified as Azospirillum brasilense. Of these strains, R7 can not only excrete 14mmol/L ammonia on the semisolid fix high nitrogen, but also produce 58.8μg/ml IAA into the medium supplemented with exogenous L-tryptophan. Conclusion: Azospirillum brasilense R7 is screened successfully which can excrete high concentration of IAA and ammonium.