Distribution And Ecology Of Ammonia Oxidizing Bacteria In The Palmer LTER Study Area

本项目将调查帕尔默长期生态研究研究区的铵氧化细菌的分布、系统发生亲和力和生态方面。氨氧化是通过反硝化将再生氮转化为二氮气体的第一步，反硝化是由三种不同的细菌群介导的三步途径。因此，氨氧化对全球氮循环很重要。在极地海洋，氨氧化和硝化-反硝化的整个过程很少受到注意，因为在那里，氨氧化和硝化-反硝化作用很重要，气候变化对生物地球化学速率的影响可能很明显。这里提出的研究目标是：A）获得有关南极氨氧化剂组成的更确切的信息; B）开始表征其生态生理学和生态学;和C）获得生物体的培养物以进行更详细的研究。水柱和海冰AOB组合的特征将被遗传学表征，不同样品中不同种类的AOB将被量化。将在整个LTER研究区测量水柱、海冰和沉积物样本中的硝化速率。将确定AOB上的放牧率，并评估它们对紫外线的敏感性。此外，将评估尿素氮作为氨氧化细菌还原氮源的重要性，并评估在适合极地地区的温度范围内硝化作用的温度响应。这项工作将提供深入了解AOB的生态学和所需的知识来模拟水柱硝化作用如何响应伴随全球气候变化的极地生态系统的变化。

This project will investigate the distribution, phylogenetic affinities and ecological aspects of ammonium-oxidizing bacteria in the Palmer Long-Term Ecological Research study area. Ammonia oxidation is the first step in the conversion of regenerated nitrogen to dinitrogen gas via denitrification, a 3-step pathway mediated by three distinct guilds of bacteria. As such, ammonia oxidation is important to the global nitrogen cycle. Ammonia oxidation and the overall process of nitrification-denitrification have received little attention in polar oceans where it is significant and where the effects of climate change on biogeochemical rates are likely to be pronounced. The goals of the studies proposed here are A) to obtain more conclusive information concerning composition of Antarctic ammonia oxidizers; B) to begin characterizing their ecophysiology and ecology; and C) to obtain cultures of the organism for more detailed studies. Water column and sea ice AOB assemblages will be characterized phylogenetically and the different kinds of AOB in various samples will be quantified. Nitrification rates will be measured across the LTER study area in water column, sea ice and sediment samples. Grazing rates on AOB will be determined and their sensitivity to UV light evaluated. In addition, the significance of urea nitrogen as a source of reduced nitrogen to AOB will be assessed and the temperature response of nitrification over temperature ranges appropriate to polar regions will be evaluated. This work will provide insights into the ecology of AOB and the knowledge needed to model how water column nitrification will respond to changes in the polar ecosystems accompanying global climate change.