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

南卡罗来纳大学的Charles R.Lovell博士和Madilyn Fletcher博士被授予研究一组被称为重氮菌的微生物的资金。这些生物也被称为固氮菌，通过从大气中捕获氮气并将其转化为其他微生物、植物和动物可以使用的形式，在营养循环中发挥着独特的作用。由于氮是所有生命系统必不可少的营养物质，所以重氮菌的活动对地球上的生命是至关重要的。重氮菌种类繁多，很多都与植物的根部有关。大多数都是特征不佳的，还有更多的还没有被发现。在这项工作中，将对与盐沼植物相关的重氮菌进行表征，以确定特定类型的重氮菌、环境因素的变化和不同寄主植物之间的关系。重氮菌将被鉴定，它们的固氮活性将利用现代基因技术进行评估。它们与特定类型的植物根的联系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，将有可能识别新的重氮菌，评估它们与植物关系的特殊性，并确定它们在时间和空间上的丰度和活性。由于重氮菌能够固定大气中的氮，它们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养护工作具有重要影响。此外，对重氮菌-植物关系的了解和新的重氮菌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素水平。该项目将通过提供研究生实习机会和与设在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.