Collaborative Research: Assessing the role of compound-specific phosphorus hydrolase transformations in the marine phosphorus cycle

合作研究：评估化合物特异性磷水解酶转化在海洋磷循环中的作用

• 批准号: 1737083
• 负责人: Solange Duhamel
• 金额: $ 55.61万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2019-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1737083&HistoricalAwards=false
• 关键词: Collaborative; Research; Assessing; role; compound

Phosphorus (P) is an essential building block for life. Because P is in short supply over vast areas of the ocean, P availability may control biological productivity, such as photosynthesis and carbon fixation, which has implications for uptake of the greenhouse gas carbon dioxide and thus climate regulation. Marine microorganisms must satisfy their nutritional requirement for P by obtaining it from seawater, where P is present in a variety of chemical forms, from simple phosphate ions (Pi) to complex dissolved organic phosphorus (DOP) molecules. The concentration of DOP vastly exceeds Pi over most ocean areas, therefore DOP is a critically important source of P for marine microbial nutrition and productivity. However, much remains unknown about the contribution of specific DOP compounds to the P nutrition, productivity, and structure of marine microbial communities. In this project, the investigators will conduct field experiments in the Atlantic Ocean and perform a series of controlled laboratory studies with pure enzymes and microbial cultures to determine how and to what extent different DOP compounds are degraded to Pi in the marine environment. Furthermore, the contribution of these compound-specific DOP molecules to microbial P nutrition, carbon fixation, and community structure will be determined, thus advancing the current state of knowledge regarding the factors that control the activity and distribution of microbial species in the ocean, and the ocean?s role in the climate system. This project will support two female junior investigators, a postdoctoral researcher, and graduate and undergraduate students. The undergraduate students will be recruited from the Marine Sciences program at Savannah State University, an Historically Black Colleges and Universities. In addition, results will be incorporated into new hands-on K-12 educational tools to teach students about microbial P biogeochemistry, including a digital game and formal lesson plans with hands-on demos. These tools will be validated with K-12 educators and will be widely accessible to the public through various well-known online platforms. These activities will thus reach a broad audience including a significant fraction of underrepresented groups.P is a vital nutrient for life. Marine microorganisms utilize P-hydrolases, such as alkaline phosphatase (AP), to release and acquire phosphate (Pi) from a wide diversity of dissolved organic P (DOP) compounds, including P-esters (P-O-C bonds), phosphonates (P-C), and polyphosphates (P-O-P). Compound-specific DOP transformations have the potential to exert critical and wide-ranging impacts on marine microbial ecology (e.g. variable DOP bioavailability among species), biogeochemistry (e.g. P geologic sequestration via formation of calcium Pi), and global climate (e.g. aerobic production of the greenhouse gas methane by dephosphorylation of methylphosphonate). However, the mechanisms and comparative magnitude of specific DOP transformations, in addition to their relative contributions to microbial community-level P demand, productivity, and structure, are not completely understood. This study will fill these knowledge gaps by tracking the fate of specific DOP pools in the marine environment. Specifically, this project will test four hypotheses in the laboratory using recombinant enzymes and axenic cultures representative of marine eukaryotic and prokaryotic plankton from high and low nutrient environments, and in the field using observational and experimental approaches along natural Pi gradients in the Atlantic Ocean. In particular, the investigators will reveal potential differences in the hydrolysis and utilization of specific DOP compounds at the community- (bulk enzymatic assays), taxon- (cell sorting of radiolabeled cells in natural samples), species- (axenic cultures) and molecular-levels (pure enzyme kinetic studies and cell-associated proteomes and exoproteomes). Results from our proposed work will provide a robust understanding of the enzymatic basis involved in the transformation of specific forms of DOP and create new knowledge on the relative contribution of these specific P sources to Pi production, marine microbial nutrition, community structure, primary productivity, and thus global carbon cycling and climate. In particular, our refined measurements of the concentration of bioavailable DOP and our unique estimates of DOP remineralization fluxes will provide critical new information to improve models of marine primary production and P cycling.

磷(P)是生命的基本组成部分。由于海洋的广大地区磷供应短缺，磷的有效性可能控制生物生产力，如光合作用和碳固定，这对温室气体二氧化碳的吸收和气候调节有影响。海洋微生物必须通过从海水中获取磷来满足它们对磷的营养需求，而海水中的磷以多种化学形式存在，从简单的磷酸盐离子（Pi）到复杂的溶解有机磷（DOP）分子。在大多数海洋区域，DOP的浓度大大超过Pi，因此DOP是海洋微生物营养和生产力的一个至关重要的P来源。然而，关于特定的有机磷化合物对海洋微生物群落的磷营养、生产力和结构的贡献，仍有许多未知之处。在这个项目中，研究人员将在大西洋进行实地实验，并使用纯酶和微生物培养进行一系列受控实验室研究，以确定不同的DOP化合物在海洋环境中如何以及在多大程度上降解为Pi。此外，这些化合物特异性DOP分子对微生物P营养、碳固定和群落结构的贡献将被确定，从而提高对控制海洋中微生物物种活动和分布的因素的认识水平。美国在气候系统中的作用。本项目资助女初级研究员2名，博士后1名，研究生和本科生2名。本科生将从萨凡纳州立大学海洋科学专业招募，这是一所历史悠久的黑人学院和大学。此外，结果将被纳入新的实践K-12教育工具，教授学生微生物P生物地球化学，包括数字游戏和正式的课程计划与实践演示。这些工具将得到K-12教育工作者的验证，并将通过各种知名的在线平台广泛向公众开放。因此，这些活动将涉及广泛的受众，包括相当一部分代表性不足的群体。磷是生命所必需的营养物质。海洋微生物利用碱性磷酸酶（AP）等P水解酶，从多种溶解的有机P （DOP）化合物中释放和获取磷酸盐（Pi），包括P-酯（P- o - c键）、磷酸盐（P- c）和多磷酸盐（P- o -P）。化合物特异性DOP转化有可能对海洋微生物生态（如物种间可变的DOP生物利用度）、生物地球化学（如通过形成钙Pi对P的地质封存）和全球气候（如甲基膦酸盐脱磷酸化产生温室气体甲烷）产生关键而广泛的影响。然而，除了它们对微生物群落水平P需求、生产力和结构的相对贡献外，具体的DOP转化的机制和相对规模尚未完全了解。这项研究将通过跟踪海洋环境中特定DOP池的命运来填补这些知识空白。具体而言，该项目将在实验室中使用重组酶和来自高营养和低营养环境的海洋真核和原核浮游生物代表的无菌培养物来测试四种假设，并在现场使用大西洋自然Pi梯度的观测和实验方法。特别是，研究人员将揭示特定DOP化合物在群落（大量酶分析），分类群（天然样品中放射性标记细胞的细胞分选），物种（无菌培养）和分子水平（纯酶动力学研究和细胞相关蛋白质组和外蛋白质组）上的水解和利用的潜在差异。我们所提出的工作结果将提供对特定形式的有机磷转化的酶学基础的有力理解，并为这些特定磷源对Pi生产、海洋微生物营养、群落结构、初级生产力以及全球碳循环和气候的相对贡献创造新的知识。特别是，我们对生物可利用DOP浓度的精确测量和我们对DOP再矿化通量的独特估计将为改进海洋初级生产和P循环模型提供重要的新信息。

项目成果

Preferential utilization of inorganic polyphosphate over other bioavailable phosphorus sources by the model diatoms Thalassiosira spp.

模型硅藻 Thalassiosira spp 优先利用无机多磷酸盐而不是其他生物可利用的磷源。

• DOI: 10.1111/1462
• 发表时间: 2019
• 期刊: Environmental Microbiology
• 影响因子: 5.1
• 作者: Diaz, Julia M.;Steffen, Rachel;Sanders, James G.;Tang, Yuanzhi;Duhamel, Solange
• 通讯作者: Duhamel, Solange

Dissolved Organic Phosphorus Utilization by Phytoplankton Reveals Preferential Degradation of Polyphosphates Over Phosphomonoesters

• DOI: 10.3389/fmars.2018.00380
• 发表时间: 2018-10-25
• 期刊: FRONTIERS IN MARINE SCIENCE
• 影响因子: 3.7
• 作者: Diaz, Julia M.;Holland, Alisia;Duhamel, Solange
• 通讯作者: Duhamel, Solange