Abstract: The present study focused on revealing the correlation between the siderophore production by siderophore-producing rhizobacteria (SPR) and selenium (Se) bioavailability in the soils by isolating, identifying and assessing on Se biofortification of SPR. Siderophore-producing bacteria were isolated and quantitative detected using chrome azural S (CAS) plate method from Guizhou Kaiyang maize rhizosphere soils. The capacity of indoleacetic acid (IAA) was detected using Salkowski colorimetry, and the identification was taken by 16S rRNA gene sequence analysis. Moreover, the Se activation test of strains in soils were carried out in lab plates. The results showed that the 5 strains had strong siderophore production ability, among which the siderophore activity unit of WD06 reached up to 73%. All strains had a certain capacity of IAA production. Furthermore, all strains could improve the water-soluble Se contents with 2.50 to 7.85 times and the available Se contents with 0.46 to 4.72 times. Identification on the three best performance strains revealed that WD01 as Klebsiella michiganensis, WD06 as Serratia marcescens and WD07 as Enterobacter xiangfangensis. The present results were helpful for soil Se biofortification via microbial strategy.

Key words: rhizobacteria, siderophore, biofortification strategy, soil selenium

摘要： 通过对高产铁载体根际菌的分离鉴定及其活化土壤硒的性能研究，揭示根际菌产铁载体与活化硒素性能的相关性。利用铬天青（chrome azural S，CAS）平板法从贵州开阳地区玉米根际土壤中筛选出产铁载体菌株，而后定量检测其产铁载体能力,采用Salkowski比色法检测其产吲哚乙酸能力,通过16S rRNA序列对其进行分析鉴定；另外，通过浸提剂提取的水溶态硒、有效硒含量高低反应菌株对土壤硒的活化能力。研究结果显示：5株菌株具有较强的铁载体分泌能力，其中菌株WD06铁载体活性单位高达73%，达到产铁载体能力较高级；各菌株均具有一定的产吲哚乙酸的能力；各菌株可对土壤中的硒起到较强的活化作用，将水溶态硒含量提高2.50~7.85倍、有效硒含量提高0.46~4.72倍；3株硒活化效果较好的菌株中，WD01经鉴定为Klebsiella michiganensis,WD06为Serratia marcescens,WD07为Enterobacter xiangfangensis。该研究结果为土壤硒微生物强化策略提供了一定的参考。

关键词: 根际菌, 铁载体, 生物强化策略, 土壤硒