Phosphonate Utilization by Eukaryotic Phytoplankton: Who, How, and Where?

真核浮游植物利用磷酸盐：谁、如何以及在哪里？

• 批准号: 1756271
• 负责人: Michael Lomas
• 金额: $ 47.2万
• 依托单位: Bigelow Laboratory for Ocean Sciences
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-02-15 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1756271&HistoricalAwards=false
• 关键词: Phosphonate; Utilization; Eukaryotic; Phytoplankton; Who

Phosphorus (P) is an essential nutrient for all living cells. It is a central component of genetic material and cellular membranes and is integral to energy production and regulating enzyme activity. In the marine environment, P occurs as inorganic (Pi) and dissolved organic (DOP) forms; the availability and concentration of these different forms of P is an important control on marine phytoplankton growth. Marine phytoplankton are single-celled photosynthetic organisms and can be both prokaryotic bacteria and eukaryotic plants. While Pi is the preferred form of P for marine phytoplankton, in large regions of the oceans it is at such low levels that it restricts phytoplankton growth. In these regions, DOP is the most important P source. The composition of the DOP pool can generally be divided into two major groups: P esters and phosphonates. All marine phytoplankton are capable of using P esters to support growth; in contrast, phosphonates have only been shown to be an important source of P in the nutrition of bacteria to date. This project will determine the ability of marine eukaryotic phytoplankton to use phosphonates as a source of P for growth. Genomic analyses will determine the metabolic response of eukaryotic phytoplankton species to growth on phosphonates as well as the relevance of phosphonate use by natural populations. It is critical to understand the metabolic capabilities of phytoplankton which control marine nutrient cycling. In addition, the project is of great value in understanding the potential impacts of a changing ocean on phytoplankton growth. The project supports reseach opportunities for undergraduates from a local community college as well as hands-on enrichment programs for an afterschool program that serves a diverse student population. Comprising up to 10% of the marine DOP pool, phosphonates have been shown to be a dynamic P pool both being assimilated and produced by marine photosynthetic bacteria. The ability of eukaryotic phytoplankton to supplement their growth with phosphonates remains vastly unexplored. Several eukaryotic phytoplankton species have been shown to use glyphosate, a chemically synthesized herbicidal phosphonate, as a P source; it remains unknown if open ocean eukaryotic phytoplankton can utilize phosphonates found naturally in the marine environment. Preliminary experiments suggest at least some eukaryotic phytoplankton are able to directly utilize extracellular phosphonates. This project characterizes the pervasiveness of phosphonate utilization within eukaryotic phytoplankton lineages and identifies the cellular underpinnings that support the acquisition of and growth on naturally occuring phosphonates. The project uses whole-cell transcriptomics and functional gene complementation assays, in addition to phylogenetic analyses, to understand the bioavailability of phosphonates and relevance of phosphonate utilization by natural eukaryotic phytoplankton populations. It is critical to understand the metabolic capabilities of phytoplankton which control marine biogeochemical cycles. This is especially important given the prediction that future oceans may become more stratified which could increase the importance of DOP, including phosphonates, in supporting phytoplankton growth.

磷（P）是所有活细胞的必需营养素。它是遗传物质和细胞膜的核心组成部分，是能量生产和调节酶活性不可或缺的一部分。在海洋环境中，P以无机（PI）和溶解有机（DOP）形式出现；这些不同形式的P的可用性和浓度是对海洋浮游植物生长的重要控制。海洋浮游植物是单细胞光合生物，可以是原核细菌和真核生物植物。尽管PI是海洋浮游植物的首选形式，但在大海的大区域中，它处于低水平，以至于限制了浮游植物的生长。在这些地区，DOP是最重要的P来源。 DOP池的组成通常可以分为两个主要组：P酯和磷酸盐。所有海洋浮游植物都能够使用P酯来支持生长。相反，磷酸盐仅被证明是迄今为止细菌营养中P的重要来源。该项目将确定海洋真核浮游植物使用磷酸盐作为生长P的来源的能力。基因组分析将确定真核浮游植物物种对磷酸盐生长的代谢反应以及自然种群使用膦酸酯的相关性。了解控制海洋营养循环的浮游植物的代谢能力至关重要。此外，该项目在理解不断变化的海洋对浮游植物增长的潜在影响方面具有巨大价值。该项目为当地社区学院的本科生提供了改编的机会，并为为多样化的学生人口提供服务的后课程计划而动手丰富计划。磷酸盐最多占海洋多头虫的10％，已证明是一种动态的P池，均被海洋光合细菌同化和产生。真核浮游植物补充磷酸盐生长的能力仍然充满探索。已经显示出几种真核浮游植物物种使用草甘膦，这是一种化学合成的磷酸草酸酯，作为P来源。尚不清楚开阔的真核浮游植物是否可以利用在海洋环境中自然发现的磷酸盐。初步实验表明，至少一些真核浮游植物能够直接利用细胞外磷酸盐。该项目表征了真核浮游植物谱系中膦酸盐利用的普遍性，并识别了支持自然发生磷酸盐的细胞基础，这些细胞基础支持支持获得和生长。该项目使用全细胞转录组学和功能基因互补分析，除了系统发育分析外，还使用天然真核生物浮游植物种群来了解磷酸盐的生物利用度以及磷酸化利用的相关性。了解控制海洋生物地球化学周期的浮游植物的代谢能力至关重要。考虑到未来海洋可能会变得更加分层的预测，这一点尤其重要，这可能会增加包括磷酸盐在内的DOP在支持浮游植物增长方面的重要性。