Microbial Observatories: Diversity of Plant-Associated Diazotrophic Bacteria and Their Distributions Within Specific Vegetation Zones Along an Environmental Gradient

博士们已获得一笔赠款。南卡罗莱纳大学（USC）的查尔斯·r·洛弗尔和玛迪琳·弗莱彻研究了一组被称为重氮营养体的微生物。这些生物——也被称为固氮细菌——通过从大气中捕获氮气并将其转化为其他微生物、植物和动物可以利用的形式，在养分循环中发挥着独特的作用。由于氮是所有生命系统必需的营养物质，重氮营养体的活动是这个星球上生命的基础。重氮营养体种类繁多，其中许多与植物的根有关。大多数的特征都很差，还有更多的尚未被发现。在这项工作中，将对与盐沼植物相关的重氮营养体进行表征，以确定特定类型的重氮营养体，环境因子变化和不同寄主植物之间的关系。将鉴定重氮营养体，并利用现代遗传技术评估其固氮活性。它们与特定类型植物根的关联将使用分子探针和先进的显微镜方法来确定。通过这种方式，将有可能鉴定新的重氮营养微生物，评估它们与植物的特异性关系，并确定它们的丰度和活动随时间和空间的变化。重氮营养体具有固定大气氮的能力，因此可以提高自然和农业系统的生产力。控制盐沼系统氮素有效性和生产力的因素对一系列恢复和保护工作具有重要意义。此外，对重氮营养物与植物关系的理解和新重氮营养物的发现可能会应用于农业和作物系统，这取决于土壤中的氮水平。该项目将通过提供研究生实习机会和与巴鲁克海洋野外实验室（BMFL）的国家河口研究保护区对接，对学生培训产生直接影响。该项目还将加强位于EPSCoR州的BMFL和USC的研究设施和培训活动。

A grant has been awarded to Drs. Charles R. Lovell and Madilyn Fletcher of the University of South Carolina (USC) to investigate a group of microorganisms called diazotrophs. These organisms - also called nitrogen-fixing bacteria - play a unique role in nutrient cycling by capturing nitrogen gas from the atmosphere and converting it into forms that can be used by other microorganisms, plants, and animals. Since nitrogen is an essential nutrient for all living systems, the activity of diazotrophs is fundamental to life on this planet. Diazotrophs are extremely diverse, and many are associated with the roots of plants. Most are poorly characterized, while still more remain undiscovered. In this work, diazotrophs associated with salt marsh plants will be characterized to determine the relationships between specific types of diazotrophs, variations in environmental factors, and different host plants. The diazotrophs will be identified and their nitrogen-fixing activity will be assessed using modern genetic techniques. Their association with specific types of plant roots will be determined using molecular probes and advanced microscopy methods. In this way, it will be possible to identify new diazotrophic microorganisms, assess the specificity of their relationships with plants, and determine their abundance and activity over time and space. Because of their ability to fix atmospheric nitrogen, diazotrophs can enhance the productivity of both natural and agricultural systems. The factors that control nitrogen availability and the productivity of salt marsh systems have important implications for a range of restoration and conservation efforts. Moreover, an understanding of diazotroph-plant relationships and the discovery of new diazotrophs may have applications to agricultural and crop systems, which depend on nitrogen levels in soils. This project will have a direct impact on student training through providing graduate student internships and interfacing with the National Estuarine Research Reserve based at the Baruch Marine Field Laboratory (BMFL). The project will also enhance research facilities and training activities at the BMFL and USC, which are located in an EPSCoR state.