Characterization of the diazotroph communities in the Subtropical North Atlantic (M60/5)

直到最近，固氮在海洋氮循环中的重要性一直被低估（Gruber和Sarmiento， 1997）。评估固氮重要性的一个基本问题是关于世界海洋重氮营养体的多样性和活动的信息缺乏。在流星60/5巡航期间，我们收集样本进行nifH基因的存在和表达分析。使用针对北大西洋样品中存在的各种重氮营养体种型的Taqman探针，我们建议对Meteor 60样品进行分析，以获得营养添加生物测定实验的定量数据。此外，我们提出表征浮游微生物群落在这些孵育过程中存在的优势16s和18s rDNA种型。浮游细菌的种型将通过16S rDNA的TRFLP分析来表征，而真核成分将主要通过18s rDNA的克隆和测序来表征。在Meteor 60/5期间进行的生物测定实验中，反应的清晰度证明了使用分子技术对各种处理中的微生物群落结构进行更完整的分析。

The importance of nitrogen fixation in the marine nitrogen cycle has been underestimated until recently (Gruber and Sarmiento, 1997). One of the fundamental questions in assessing the importance of nitrogen fixation is the paucity of information concerning the diversity and activity of marine diazotrophs in the world s ocean. During the Meteor 60/5 cruise, we collected samples for the analysis of nifH gene presence and expression. Using Taqman probes specific for various diazotrophs phylotypes present in our North Atlantic samples, we propose here to analyze the Meteor 60 samples to obtain quantitative data from nutrient addition bioassay experiments. In addition, we propose to characterize the dominant 16 S and 18 S rDNA phylotypes of the planktonic microbial community present during these incubations. The bacterioplankton phylotypes will be characterized both by TRFLP analysis of 16S rDNA while the eukaryotic component will be characterized mainly by cloning and sequencing of the 18 S rDNA. The clarity of the response from the bioassay experiments conducted during the Meteor 60/5 justifies a more complete analysis of the microbial community structure in the various treatments, using molecular techniques.