水稻内生固氮菌Herbaspirillum seropedicae DX35的筛选及其促生特性

Rice endogenous nitrogen fixing and growth promoting bacterium Herbaspirillum seropedicae DX35

【目的】筛选水稻高效内生固氮菌,并对其促生特性进行分析。【方法】从湖南祁阳中国农业科学院红壤实验站具30年长期稻-稻-绿肥轮作定位试验田中采集水稻根并分离内生细菌,通过乙炔还原法测定其固氮酶活性,筛选出固氮活性较高的菌株,运用16S rRNA基因、nifH基因以及脂肪酸分析确定其发育地位。同时采用Salkowski比色法测定其生长素的分泌能力,CAS蓝色平板检测法测定产铁载体能力,溶磷圈法测定溶磷性,对其促生特性进行分析。【结果】共分离获得48株内生菌,其中DX35固氮酶活性最高,经鉴定属于Herbaspirillum seropedicae,其固氮酶活性为181.21 nmol C2H4/(mg protein·h),约是参比菌株Azotobacter chroococcum ACCC10006的10倍。另外该菌株还具有一定的分泌铁载体能力和溶磷特性。【结论】DX35属于H.seropedicae,是一种高效内生固氮菌,具有很好的生产应用前景。

［Objective］To screen efficient nitrogen fixation endophytes from rice and to analyze their growth-promoting properties．［Method］We isolated strains from the roots of rice in the field where it has a rice-rice-green manure rotation system for 30 years．Efficient strains were screened by acetylene reduction assay． Phylogenetic analysis is based on 16S rRNA gene，nifH gene and the composition of fatty acid． In addition，we also detected the ability of indole acetic acid secretion through the Salkowski colorimetric method，measured the production of siderophore through the blue plate assay and detected phosphate solubilization，to analyze the growth-promoting properties．［Result］ A total of 48 strains were isolated，in which DX35 has the highest nitrogenase activity．It belongs to Herbaspirillum seropedicae after identification．Its nitrogenase activity （181.21 nmol C2H4/（mg protein·h）） was 10 times as much as the reference strain Azotobacter chroococcum ACCC10006．In addition，it also can secrete siderophore and solubilize phosphorus．［Conclusion］Strain DX35，belonging to Herbaspirillum seropedicae，is an efficient nitrogen fixation endophytes．