The Ocean Nitrogen Imbalance Paradox: Environmental Controls on the Denitrification Isotope Effect

智力优势：这项研究将测试反硝化同位素效应的幅度对与海洋环境有关的培养条件的敏感性。同位素效应的幅度将探讨与电子供体，微量氧，和温度，在分批和连续培养实验的发酵。拟议的工作还将涉及测量的呼吸硝酸还原酶的酶同位素效应的微生物，其酶的活性之间的文化测量，和检查的细胞硝酸盐运输动力学的微生物菌株。这些实验旨在揭示同位素效应幅度调制的生理基础，这将进一步解决环境中的这种表现。更广泛的影响：关于这项研究的更广泛意义和重要性，这些新的实验数据将为在海洋模型中整合氮同位素动力学提供基础，以测试关键环境参数如何影响全球海洋氮同位素分布。 此外，该提案还将为一名研究生提供支助，向其介绍从微生物学和酶学到海洋学和稳定同位素地球化学等广泛的技术和分支学科。该项目涉及一名早期职业女性PI，她将在整个项目中指导一名研究生。

Intellectual Merit: This study will test the sensitivity of the amplitude of the denitrification isotope effect to culture conditions pertinent to the ocean environment. The isotope effect amplitude will be explored with respect to electron donor, trace oxygenation, and temperature, in both batch and continuous culture experiments of denitrifiers. The proposed work will also involve measurements of the enzymatic isotope effect of the respiratory nitrate reductase of denitrifiers, measurements of its enzymatic activity among cultures, and examination of cellular nitrate transport kinetics of denitrifying strains. The experiments are designed to reveal the physiological basis of the modulation of the isotope effect amplitude, which will further resolve this manifestation in the environment. Broader Impacts: In regards to the broader significance and importance of this study, these new experimental data will provide a basis for integration of nitrogen isotope dynamics in ocean models to test how key environmental parameters can affect the global ocean distribution of nitrogen isotopes. Moreover, the proposal will provide support for a graduate student, who will be introduced to a broad range of techniques and sub-disciplines, from microbiology and enzymology, to oceanography and stable isotope biogeochemistry. The project involves an early career female PI, who will mentor one graduate student throughout the project.