Understanding microbial control of dissolved organic nitrogen (DON) in the ocean: New amino acid tracers for bacterial source and cycling of refractory DON

了解海洋中溶解有机氮 (DON) 的微生物控制：用于细菌来源和难治性 DON 循环的新型氨基酸示踪剂

• 批准号: 2124180
• 负责人: Matthew McCarthy
• 金额: $ 84.97万
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2124180&HistoricalAwards=false
• 关键词: Understanding; microbial; control; dissolved; organic

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).One of the most mysterious components of the global nitrogen cycle is the vast amount of dissolved nitrogen-containing organic molecules (dissolved organic nitrogen, or “DON”) which exist in the ocean. The identities of these molecules are mostly unknown, but they are important in the ocean’s biological and geochemical cycles, because they persist for many thousands of years and in many cases these molecules are too complex for simple organisms at the base of the food web to use. This project will develop new chemical tools to understand this material, including stable isotopes, radioisotopes, and the chirality of amino acids. Together, this new set of tracers will focus on the roles of marine bacteria as sources and creators of persistent dissolved organic nitrogen. The project will begin in the laboratory, where the team will first grow large cultures of ocean algae. Natural ocean bacteria will then be added, and investigators will measure the proposed new tracers in dissolved nitrogen materials created. These data will reveal how the proposed tracers work: how and when they are produced, if they map to bacterial sources, and how bacterial degradation may affect them. The investigators will then conduct a series of field expeditions at contrasting sites on the California coast and in the central Pacific Ocean, isolating large amounts of natural dissolved organic nitrogen. The team will apply what has been learned in the lab together with the first ever radiocarbon measurements on individual tracer molecules. Together these activities will open a new window into sources and cycling of the critical marine dissolved organic nitrogen material. The project will support the education, training, and career development of a graduate student, a postdoctoral researcher, and undergraduate students from underrepresented groups, who will be recruited to receive real hands-on laboratory and field experience. This project will develop three new amino acid–based proxies for bacterial source and alteration of dissolved organic nitrogen: 1) compound-specific stable carbon isotope fingerprinting of essential amino acids, 2) a recently discovered suite of new D-amino acids found to be concentrated in radiocarbon-old, low molecular weight DON material, and 3) individual amino acid radiocarbon values for key hypothesized tracer amino acids. The investigators hypothesize that refractory ocean DON is essentially completely microbial, however that it is also far more diverse than has previously been understood in terms of its sources, molecular composition, and especially cycling rates. In particular, the project will test the idea of completely different DON origin, molecular composition, and cycling rates in high vs. low molecular weight DON fractions throughout the water column. Autotrophic and heterotrophic bacterial growth / degradation experiments will test assumptions about the sources and degradation- related changes to D/L and stable carbon isotope signatures. Synoptically making these measurements together with individual amino acid radiocarbon values in high productivity coastal vs. oligotrophic Pacific gyre DON in both surface and deep ocean will allow understanding the diversity of DON bacterial sources, degradation impacts, and N-specific cycling rates for the first time.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该奖项是根据2021年《美国救援计划法》（公法117-2）全部或部分资助的。全球氮循环中最神秘的组成部分之一是大量溶解的含氮有机分子（溶解的有机氮，或“ DON”），存在于海洋中。这些分子的身份大多是未知的，但是它们在海洋的生物学和地球化学周期中很重要，因为它们持续了数千年，在许多情况下，这些分子对于食物网基底部的简单生物来说太复杂了。该项目将开发新的化学工具来了解该材料，包括稳定的同位素，放射性同位素和氨基酸的手性。这组新的示踪剂将共同关注海洋细菌作为持续溶解有机氮的来源和创造者的作用。该项目将在实验室开始，该团队将首先种植大量的海洋藻类文化。然后，将添加天然海洋细菌，研究人员将测量溶解的氮材料中提出的新示踪剂。这些数据将揭示提出的示踪剂的工作方式：如何以及何时产生它们，是否映射到细菌来源以及细菌降解如何影响它们。然后，调查人员将在加利福尼亚海岸和中太平洋的对比地点进行一系列现场探险，从而隔离大量的天然溶解有机氮。该团队将应用实验室中学到的知识，以及在单个示踪剂分子上的第一个放射性碳测量值。这些活动将共同为关键海洋溶解有机氮材料的来源和循环打开新窗口。该项目将支持研究生，博士后研究员和本科生的教育，培训和职业发展，他们将被招募以获得真正的动手实验室和现场经验。该项目将开发三个新的基于氨基酸的代理，用于细菌来源和溶解的有机氮的改变：1）必需氨基酸的化合物特异性稳定的碳同位素指纹识别，2）最近发现的新的D-氨基酸的套件，用于在雷克比型，低的分子体重唐型浓度的新型D-氨基酸中，以及3）浓缩的don radioth，3）。示踪剂氨基酸。研究人员假设难治性的海洋DON基本上是完全微生物，但是它的多样性也比以前所理解的要多样化得多，从其来源，分子组成，尤其是循环速率。特别是，该项目将在整个水柱中测试完全不同的DON起源，分子组成和循环速率DON的想法。自养和异养细菌的生长 /降解实验将测试有关源和降解与D / L和稳定碳同位素特征的相关变化的假设。在高生产率中，沿海与贫营养的太平洋Gyre Don在地面和深海中的高生产率与少亲子的太平洋Gyre Don中进行概括性进行这些测量，将使Don细菌来源的多样性，退化影响的多样性，降级影响以及首次通过Infortial Indortiral te Inderial Indertial te Inderial reportial Meritial ratunial reportial te Indiem te eymerial teemportial of Inderial of Indilection teem deemporial of nsf sfor。影响审查标准。