Role of variable picoplankton cellular phosphorus turnover and allocation in marine phosphorus cycling

可变超微型浮游生物细胞磷周转和分配在海洋磷循环中的作用

基本信息

批准号：
1434914
负责人：
Solange Duhamel
金额：
$ 23.44万
依托单位：
Columbia University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2014
资助国家：
美国
起止时间：
2014-09-01 至 2017-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1434914&HistoricalAwards=false
关键词：
Role variable picoplankton cellular phosphorus

项目摘要

Phosphorus is a key element for life, often present in low amounts in the vast central regions of the ocean and sometimes reaching limiting concentrations for biological productivity. Microbial uptake of dissolved phosphorus is an important lever in controlling both microbial production and the fate and cycling of marine phosphorus. This project will investigate the hypothesis that in oligotrophic environments, microbial cellular turnover of phosphorus occurs more rapidly than cellular biomass turnover, leading to a significant return of phosphorus to the dissolved pool. This rapid return of phosphorus could resupply the pool of bioavailable phosphorus, impacting microbial dynamics and fueling significant recycling of phosphorus in the surface ocean. In particular, this research will use field samples to determine the rates of cellular phosphorus and biomass turnover in the dominant groups of very small algae and bacteria inhabiting the phosphorus-depleted, surface waters of the Sargasso Sea (the region of the central North Atlantic Ocean near Bermuda). The project will be co-directed by two early-career women scientists. Their educational efforts will include training of an undergraduate student assistant as well as public educational outreach to K-12 students.A primary objective in the study of biogeochemical cycles is linking chemical fluxes to the activity of organisms. This work will make fundamental contributions to the understanding of the biogeochemical cycling of phosphorus by linking phosphorus fluxes in the surface ocean to the activity of specific groups of microbes, and providing a mechanistic framework for the factors that control these fluxes. A significant, novel product of this research will be the determination of cellular phosphorus turnover rates relative to biomass turnover rates for individual picoplankton groups in the open ocean. To build a mechanistic understanding of the processes controlling these rates, this project will also determine the variation in picoplankton allocation of phosphorus into intracellular biochemicals. Field measurements will be augmented with experiments on axenic cultures, representative of the cell-sorted groups from the Sargasso Sea, to conduct more detailed biochemical analyses. The research team will utilize a unique suite of tools to make novel measurements from environmental samples: flow cytometry and fluorescence activated cell sorting will be combined with radioisotope labeling and biochemical analyses to quantify cell-specific phosphorus fluxes and characterize the chemical speciation of these fluxes. The significance of a high ratio of cellular phosphorus turnover rate to biomass turnover rate would be two-fold: (1) the amount of phosphorus in microbial biomass would underestimate the total phosphorus demand necessary to support microbial growth, and (2) significant recycling of dissolved phosphorus may occur in the surface ocean through microbial uptake and rapid return to the dissolved pool. By measuring these rates in field samples, the team expects to answer crucial questions about the relative impact of different microbial groups on surface ocean phosphorus fluxes and the cellular dynamics that drive these fluxes.

磷是生命的关键要素，通常在海洋广阔的中央区域中以低量存在，有时达到生物生产力的极限浓度。溶解磷的微生物摄取是控制微生物产生以及海洋磷的命运和循环的重要杠杆。该项目将研究以下假设：在贫营养环境中，微生物细胞的磷的细胞更新比细胞生物量更高更快，从而导致磷向溶解池的显着回归。磷的这种快速回归可以补充可生物利用的磷的池，影响微生物动力学，并为地表海中磷的大量回收加油。特别是，这项研究将使用现场样品来确定非常小的藻类和细菌的细胞磷和生物量转移率的速率，居住在萨尔加索海（萨尔加索海（Bermuda）附近北大西洋中部地区的磷酸盐，地表水中）。该项目将由两位早期职业女科学家共同指导。他们的教育工作将包括对本科生助理的培训以及向K-12学生进行公共教育宣传。研究生物地球化学周期的主要目标是将化学通量与生物体的活动联系起来。这项工作将通过将地面海洋中的磷通量与特定微生物的活性联系起来，并为控制这些通量的因素提供机械框架，从而对磷的生物地球化学循环做出基本贡献。这项研究的一个重要新产品将是确定相对于开海中单个皮克力全体组的生物量转离率的细胞磷离职率。为了建立对控制这些速率的过程的机械理解，该项目还将确定磷在细胞内生物化学物质中的磷兰克顿分配的变化。通过对萨尔加索海细胞分类基团的轴突培养物进行实验，将对现场测量进行增强，以进行更详细的生化分析。研究团队将利用一套独特的工具来从环境样本中进行新的测量：流式细胞仪和荧光激活的细胞分选将与放射性同位素标记和生化分析结合使用，以量化细胞特异性磷酸液并表征这些通量的化学物质。高比率的高比例的细胞磷离职率与生物量离职率的重要性是两个方面：（1）微生物生物量中的磷量将低估支持微生物生长所需的总磷需求，并且（2）溶解的磷酸磷酸化的显着回收可能会通过微生物返回量返回量，并返回量库中。通过测量现场样本中的这些速率，该团队希望回答有关不同微生物基团对表面海洋磷通量的相对影响以及驱动这些通量的细胞动力学的关键问题。