Collaborative Research: Assessing the role of polyphosphate production and cycling in marine ecosystem functioning.

磷(P)是所有生命形式所必需的重要营养物质。在海洋中，维持着全球一半的光合作用和氧气供应，磷的稀缺可能会限制生物生产力、二氧化碳吸收，从而限制气候。人类活动正在加速磷等营养物质向海洋的输送，但氮的输入速度更快。这种不平衡可能会增加海洋生态系统的磷胁迫水平，使海洋生产力越来越受到磷供应的控制。鉴于磷在维持现在和未来的海洋健康和生态系统服务方面的关键作用，有必要全面了解其在海洋环境中的利用和命运。在这个项目中，研究小组调查了海洋聚磷酸盐(Polyp)，这是一种无处不在但却鲜为人知的磷，由所有生物制造。为了填补关于海洋息肉的主要知识空白，研究人员正在克服主要技术障碍，以产生第一个海洋微生物中息肉的定量测量结果。这些测量是在实验室微生物培养上进行的，以及来自高磷供应环境的野外样本，如加州当前的生态系统，或极低磷供应环境，如地中海。此外，研究小组正在研究这些不同生物和环境中海洋息肉的细胞功能，以阐明其在生物磷营养中的作用。这项工作有助于推进跨学科的息肉研究，包括陆地科学，甚至癌症研究，并在磷生物修复方面有广泛的应用。该项目支持两名女科学家实验室中的一名博士后研究员、一名研究生和几名本科生。正在通过这一项目制作和传播新的教育工具，向公众传授海洋息肉知识。一名K12教师参与了这项工作，并在网上向他们的教室和广大观众传达了研究结果。聚磷在海洋系统中普遍存在，在微生物磷营养和磷矿物形成和封存方面发挥着关键作用。在这些方面，息肉有可能塑造长期和短期的海洋磷循环、初级生产力、微生物生态和全球气候。然而，主要的知识差距仍然存在。由于技术限制，科学界目前缺乏对海洋息肉池、其链长和生物起源的定量了解。此外，鉴于息肉作为磷储存分子的观点，最近的观察表明，颗粒状息肉在低磷环境中优先保留，这对其生态生理功能提出了新的问题。为了缩小这些知识差距，我们提出了两个研究问题：问题1：息肉在不同微生物群和环境条件下的总含量和链长分布是什么？问题2：颗粒状息肉的产生如何在广泛的磷供应范围内促进微生物磷需求和化学计量？检验了以下假设：H1(Q1)：功能和环境多样化的浮游生物产生广泛范围的息肉链长和浓度。H2(Q2)：在低等电点环境中的优先保留性与其作为磷储存分子的作用可以通过分类学和生理因素的组合来协调。这些假设在实验室中使用典型的海洋浮游生物培养进行了验证，并在现场使用沿太平洋和地中海自然等密度梯度的观测方法进行了验证。应用一种使用质谱学的以磷为靶标的新方法，该团队正在解析海洋息肉含量和物种形成的前所未有的详细程度。通过将细胞分类与元素、生化和放射性示踪剂分析相结合，该团队正在获得对息肉生理学及其在海洋中的循环的机械理解。该项目得到了生物海洋学和化学海洋学计划的支持。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Phosphorus (P) is a vital nutrient required by all forms of life. In the ocean, which sustains half of global photosynthesis and oxygen supply, P can be scarce enough to constrain biological productivity, carbon dioxide uptake, and therefore climate. Human activity is accelerating the delivery of nutrients like P to the ocean, but rates of nitrogen inputs are even greater. This imbalance may increase levels of P stress in marine ecosystems, placing ocean productivity more and more under the control of P supply. Given the critical role of P in sustaining ocean health and ecosystem services now and into the future, a comprehensive understanding of its utilization and fate in the marine environment is necessary. In this project, the research team investigates marine polyphosphate (polyP), a ubiquitous yet poorly understood form of P made by all living organisms. To close major knowledge gaps on marine polyP, the investigators are overcoming major technical barriers to produce the first quantitative measurements of polyP in marine microorganisms. These measurements are being conducted on laboratory microbial cultures, as well as field samples from environments with high P supply, such as the California Current Ecosystem, or very low P supply, such as the Mediterranean Sea. In addition, the research team is resolving the cellular function of marine polyP across these different organisms and environments in order to clarify its role in biological P nutrition. This work helps advance polyP research across disciplines, including terrestrial science and even cancer research, and has broad application to P bioremediation. This project supports a postdoctoral researcher, a graduate student, and several undergraduate students in the labs of two female scientists. New educational tools to teach the public about marine polyP are being produced and disseminated through this project. A K12 teacher is participating in the work and communicating the findings to their classrooms and to broad audiences online.PolyP is ubiquitous in marine systems, where it plays critical roles in microbial P nutrition and P mineral formation and sequestration. In these ways, polyP has the potential to shape long- and short-term marine P cycling, primary productivity, microbial ecology, and global climate. However, major knowledge gaps still exist. Due to technical limitations, the scientific community currently lacks a quantitative understanding of marine polyP pools, their chain lengths, and biological origins. Furthermore, given the view of polyP as a P storage molecule, recent observations pointing to the preferential retention of particulate polyP in low phosphate (Pi) environments raise new questions about its ecophysiological functions. To close these knowledge gaps, two research questions are addressed: Q1: What is the total content and chain length distribution of polyP across different microbial groups and environmental conditions? Q2: How do the production of particulate polyP contribute to microbial P demand and stoichiometry across a broad range in Pi availability? The following hypotheses are tested: H1 (Q1): Functionally and environmentally diverse plankton produce a broad range of polyP chain lengths and concentrations. H2 (Q2): The preferential retention of polyP in low Pi environments can be reconciled with its role as a P storage molecule by a combination of taxonomic and physiological factors. These hypotheses are tested in the laboratory using representative cultures of marine plankton and in the field using observational approaches along natural Pi gradients in the Pacific Ocean and Mediterranean Sea. Applying a new P-targeted method using mass spectrometry, the team is resolving an unprecedented level of detail in marine polyP content and speciation. By combining cell sorting with elemental, biochemical, and radiotracer analyses, the team is gaining a mechanistic understanding of polyP physiology and its cycling in the ocean.This project is supported by the Biological Oceanography and Chemical Oceanography Programs.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.