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，是能量产生和调节酶活性的组成部分。在海洋环境中，磷以无机（Pi）和溶解有机（DOP）形式存在;这些不同形式的磷的有效性和浓度是海洋浮游植物生长的重要控制因素。海洋浮游植物是单细胞光合生物，既可以是原核细菌，也可以是真核植物。虽然Pi是海洋浮游植物首选的P形式，但在大面积的海洋中，它的水平很低，限制了浮游植物的生长。在这些地区，DOP是最重要的磷源。DOP池的组成通常可分为两大类：磷酸酯和膦酸酯。所有的海洋浮游植物都能够利用磷酯来支持生长;相反，膦酸盐迄今为止只被证明是细菌营养中P的重要来源。该项目将确定海洋真核浮游植物利用膦酸盐作为生长磷源的能力。基因组分析将确定真核浮游植物物种对膦酸盐生长的代谢反应以及自然种群使用膦酸盐的相关性。了解浮游植物的代谢能力是控制海洋营养循环的关键。此外，该项目在了解不断变化的海洋对浮游植物生长的潜在影响方面具有重要价值。该项目支持当地社区大学本科生的研究机会，以及为服务于不同学生群体的课后计划提供实践丰富计划。磷酸盐在海洋DOP库中占10%以上，是一种动态的磷库，既被海洋光合细菌吸收，又被海洋光合细菌产生。真核浮游植物的能力，以补充其生长与膦酸盐仍然大大未开发。几种真核浮游植物物种已被证明使用草甘膦，化学合成的除草膦酸盐，作为磷源;它仍然是未知的，如果开放的海洋真核浮游植物可以利用天然存在于海洋环境中的膦酸盐。初步实验表明，至少有一些真核浮游植物能够直接利用细胞外的膦酸盐。该项目的特点膦酸盐利用的普遍性真核浮游植物谱系，并确定支持收购和自然发生的膦酸盐的增长的细胞基础。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，了解天然真核浮游植物种群的膦酸盐的生物利用度和膦酸盐利用的相关性。了解浮游植物的代谢能力是控制海洋生物地球化学循环的关键。这一点特别重要，因为预测未来的海洋可能会变得更加分层，这可能会增加DOP的重要性，包括膦酸盐，在支持浮游植物生长。