Collaborative Research - Taxon-Specific Variability of Organiz Matter Production and Remineralization Potential

知识专长：海洋磷循环的特征是溶解无机磷（DIP）和溶解有机磷（DOP）的吸收和分解之间的紧密耦合。DIP被整合到广泛的细胞化合物中，这些化合物是能量储存、遗传物质和细胞结构的组成部分。细胞死亡和自溶、渗出、病毒裂解和放牧都导致DOP释放到环境中，在环境中DOP可以解聚、水解、再同化、通过吸收到沉降颗粒上而去除或在周围环境中积累。以这种方式，在海洋环境中的P的形式和组成在很大程度上由微生物的代谢活动控制，并与碳（C）和氮（N）的循环密切相关，因为颗粒有机P（POP）和DOP以多种形式（包括酯、磷脂和膦酸酯）与C和N结合。因此，考虑海洋P循环是最相关的P转换被视为在海洋水柱的营养和能量流的一部分。在生态系统尺度上，生产力和呼吸在公海的平衡是由潜在的限制营养物质，如C，N和P的可用性，因此，了解耦合的C，N和P循环是中央的决定的长期控制的幅度和变化的初级生产和颗粒出口。尽管如此，同时措施的溶解有机碳（DOC），溶解有机氮（DON）和DOP和生产和分解过程的信息相对缺乏，阻碍了了解这些池的耦合动力学的进展。溶解有机物（DOM）动态的最新研究表明，大偏离Redfield轨迹驱动的浮游植物物种组成的变化，化学计量和化学组成的有机物生产，微分不稳定性的有机化合物和优先的氮和磷的异养细菌。此外，有越来越多的证据表明，潜在的温室气体的释放发生通过DOP水解。在这项研究中，研究人员将表征的组成，不稳定性和平衡化学计量的有机P-C-N产生的生态重要的光合属。 他们将进行一系列原位和基于实验室的生物测定，其中将从原绿球藻和含磷酸盐的束毛藻菌株中分离的颗粒物（POM）和DOM添加到天然微生物种群中，并在实验室和海上进行孵育。 假设驱动的实验将解决以下目标：（1）确定元素（P-C-N）的化学计量和生物分子的变化（31 P-核磁共振）发生在响应于外源性添加的束丝藻和原绿球藻POM和DOM的异养细菌的天然种群，估计不稳定和半不稳定的有机物质产生的生态重要的属和测量潜在的好氧产生的温室气体（甲烷和乙烷）。(2)在NPSG的季节周期的相反阶段（夏季/冬季）启动分解实验，以捕获具有不同初始代谢状态和群落结构的不同微生物组合。更广泛的重要性：研究目标的实施将有助于通过数据共享和批判性话语建立合作网络。更广泛的教育影响包括为参与该项目的青年科学家提供广泛的跨学科和实验室间培训，并为提高妇女在科学领域的地位提供机会。研究重点将纳入所教授的课程，包括传播海洋科学，科学成果将通过出版物、参加会议和讲习班以及维护研究博客来分享。研究人员将与NSF资助的微生物研究和教育中心的教育工作人员合作，开发一个科学工具包，以说明生物学在元素循环中的作用。该资料袋将分发给所有伙伴机构。这项研究的更广泛的社会效益是提高了对关键生物区系在元素循环中的作用以及对基本海洋生境中初级生产和出口生产的调节的认识。

INTELLECTUAL MERIT: The marine phosphorus (P) cycle is characterized by tight coupling between the uptake and decomposition of dissolved inorganic P (DIP) and dissolved organic P (DOP). DIP is incorporated into a broad range of cellular compounds integral for energy storage, genetic material and cell structure. Cell death and autolysis, exudation, viral lysis and grazing all lead to the release of DOP into the environment where it can be depolymerized, hydrolyzed, reassimilated, removed by absorption onto sinking particles or accumulate in the surrounding environment. In this manner, the form and composition of P in the marine environment is largely controlled by the metabolic activity of microorganisms and is intimately linked to the cycling of carbon (C) and nitrogen (N) as particulate organic P (POP) and DOP is bound to C and N in multiple forms, including esters, phospholipids and phosphonates. Thus, a consideration of marine P cycling is most relevant when P transformations are viewed as part of the nutrient and energy flow in the oceanic water column. At the ecosystem scale, the balance of productivity and respiration in the open ocean is regulated by the availability of potentially limiting nutrients such as C, N and P. Therefore, understanding the coupling of C, N, and P cycles is central to the determination of the long-term controls of the magnitude and variability of primary production and particle export. Nonetheless, a paucity of simultaneous measures of dissolved organic carbon (DOC), dissolved organic nitrogen (DON) and DOP and a relative lack of information on production and decomposition processes have hindered progress in understanding the coupled dynamics of these pools. Recent studies of dissolved organic matter (DOM) dynamics show large departures from Redfield trajectories driven by alterations in phytoplankton species composition, the stoichiometry and chemical composition of organic matter production, differential lability of organic compounds and preferential remineralization of N and P by heterotrophic bacteria. Furthermore, there is mounting evidence of the potential liberation of greenhouse gases occurring via DOP hydrolysis.In this research, the investigators will characterize the composition, lability and remineralization stoichiometry of organic P-C-N produced by ecologically significant photosynthetic genera. They will conduct a series of in situ and laboratory-based bio-assays where particulate (POM) and DOM isolated from Prochlorococcus and phosphonate-containing strains of Trichodesmium are added to natural microbial populations and incubated in the laboratory and at sea. Hypothesis driven experiments will address the following objectives:(1) Determine the elemental (P-C-N) stoichiometry and biomolecular alterations (31P-nuclear magnetic resonance) occurring in response to exogenous additions of Trichodesmium and Prochlorococcus POM and DOM to natural populations of heterotrophic bacteria, estimate the labile and semi-labile fraction of organic material generated by ecologically significant genera and measure potential aerobic production of select greenhouse gases (methane and ethane). (2) Initiate decomposition experiments in the NPSG at opposing phases of the seasonal cycle (summer/winter) in order to capture varying microbial assemblages having different initial metabolic status and community structure. BROADER IMPACTS: Implementation of the research objectives will serve to build collaborative networks through data sharing and critical discourse. Broader educational impacts include the provision of extensive interdisciplinary and inter-laboratory training for the young scientists included in the project and opportunities for the advancement of women in science. Research highlights will be incorporated into courses taught, including Communicating Ocean Science and scientific findings will be shared via publications, participation in conferences and workshops and maintenance of a research blog. Partnering with education staff at the NSF-funded Center for Microbial Research and Education, the investigators will develop a science kit to illustrate the role of biology in elemental cycles. The kit will be made available for distribution to all partner institutions. The broader societal benefits of the research are an increased understanding of the role of key biota in elemental cycling and the regulation of primary and export production in a fundamental oceanic habitat.