Community Dynamics Localization and Fixation Potentials of Marine N2-Fixing Microbial Assemblages

长期的氮缺乏是世界上大部分海洋的特点。微生物固氮有助于缓解这些缺陷。与蓝藻相比，真细菌作为固氮剂的作用受到的关注较少。该项目利用最近开发的免疫学和分子技术，重点研究氮枯竭的北卡罗来纳州沿海水域中真细菌的作用，以提供一套针对细胞的荧光和同位素分析，以了解底栖和浮游生境中的细菌种群和群落动态。这样的技术和分析允许鉴定有能力并被诱导固定N的细胞，并提供了一种在整个种群DNA中检测固氮酶基因存在的方法。这些技术将允许(1)关于微生物固氮潜力及其位置的直接、定量的信息，(2)对调节固氮酶基因表达的环境条件进行评估，以及(3)对最近描述的具有数字和营养重要性的微浮游蓝藻的固氮能力进行评估。

Chronic combined nitrogen deficiencies characterize vast segments of the world's oceans. Microbial nitrogen fixation helps to alleviate these deficiencies. The role of eubacteria as nitrogen fixers has received less attention than cyanobacteria. This project focuses on the role of eubacteria in N-depleted North Carolina coastal waters using recently developed immunological and molecular techniques to provide a cell specific set of fluorescence and isotopic assays of bacterial population and community dynamics in benthic and planktonic habitats. Such techniques and assays allow for identification of cells competent and induced to fix N, and provide a means to detect the presence of nitrogenase genes in total population DNA. These techniques will allow (1) direct, quantitative information on microbial N fixation potentials and sites thereof, (2) assessment of environmental conditions that regulate nitrogenase gene expression, and (3) evaluation of recently described, numerically and trophically important picoplanktonic cyanobacteria for their N fixing capabilities.