Quantifying the role of Group I Crenarchaeota in the marine nitrogen cycle using cultures and environmental monitoring of ammonia oxidation, 16S rRNA genes and lipid biomarkers

分子微生物生态学的最新进展颠覆了海洋氮循环的典型范例。全球固氮的估计定期向上修订，非传统的细菌反硝化途径称为厌氧氨氧化，现在被认为是负责全球反硝化的重要部分，氨氧化菌的发现需要重新评估传统硝化细菌对全球氮循环的贡献。虽然环境基因测序和地球化学研究对这些发现至关重要，但如果没有对纯培养的代表性生物体进行研究，就不可能获得许多新的认识。自1992年被发现以来，嗜温海洋古生物的生态作用一直是一个谜，很大程度上是因为缺乏一个培养的代表。一个嗜温海洋Crenarchaea现在是在文化沿着的几条线的证据表明，这和许多其他远洋海洋Crenarchaea氧化氨，以获得所需的能量，以维持自养碳固定。海洋泉古菌的分布及其编码氨氧化酶的基因表明，这些生物负责氧化海洋中很大一部分的还原氮库。本计画将探讨细菌氨氧化的速率与效率，以及细菌与细菌在氨氧化中的相对角色。 该项目独特地结合了文化工作，分子生物学，有机地球化学和实地调查，成为海洋Crenarchea在氮的地球化学循环中的作用的首批研究之一。 研究生和本科生将获得跨学科研究项目的专业知识，结合微生物学，分子生物学和生物标志物的尖端方法，PI将与最近资助的并即将在其家乡机构建立的COSEE中心进行互动。

Recent advances in molecular microbial ecology have overturned canonical paradigms of the marine nitrogen cycle. Estimates of global nitrogen fixation are regularly revised upward, the non-traditional bacterial denitrification pathway known as anammox is now thought to be responsible for a significant portion of global denitrification, and the discovery of ammonia-oxidizing Archaea necessitates a reevaluation of the contribution of traditional nitrifying bacteria to the global nitrogen cycle. While environmental gene sequencing and geochemical studies were critical to these discoveries, much of this new understanding could not have been gained without the aid of studies on representative organisms in pure culture. Since their discovery in 1992, the ecological role of mesophilic marine Archaea has remained a mystery due in large part to the lack of a cultured representative. A mesophilic marine Crenarchaea is now available in culture along with several lines of evidence that this and many other pelagic marine Crenarchaea oxidize ammonia to obtain the energy needed to sustain autotrophic carbon fixation. The distribution of marine Crenarchaea and their genes encoding ammonia-oxidizing enzymes, suggests that these organisms are responsible for the oxidation of a significant portion of the ocean's reduced nitrogen pools. This project will examine the rate and efficiency of Archaeal ammonia-oxidation, and the relative role of Bacteria and Archaea in ammonia-oxidation. The project uniquely combines culture work, molecular biology, organic geochemistry and field investigations into one of the first studies of the role of marine Crenarchaea in the biogeochemical cycling of nitrogen. Graduate and undergraduate students will gain expertise in an interdisciplinary research project, combining cutting edge methods in microbiology, molecular biology and biomarkers, and the PIs will interact with a recently funded and soon to be established COSEE center at their home institution.