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How important is prokaryotic photoheterotrophy in ecosystems of the Atlantic Ocean from 40oS to 40oN?

原核光异养在南纬 40 度到北纬 40 度的大西洋生态系统中有多重要？

基本信息

批准号：
NE/H007083/1
负责人：
David Scanlan
金额：
$ 2.5万
依托单位：
University of Warwick
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2010
资助国家：
英国
起止时间：
2010 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FH007083%2F1
关键词：
How important prokaryotic photoheterotrophy ecosystems

项目摘要

The aim of the proposal is to find out how important photoheterotrophy is in the open ocean - the Earth's largest ecosystem, of profound importance to global biogeochemistry and climate. Photoheterotrophic prokaryotes use light for energy but cannot use carbon dioxide as their sole carbon source and consequently use organic molecules from the environment to satisfy their carbon requirements. Despite considerable advances in the understanding of several photoheterotrophic mechanisms the role of solar radiation in the metabolism of bacterioplankton in the ocean is difficult to assess, although it is already apparent that CO2 fixation by prokaryotic cells may be only a part of the picture. The project proposes to experimentally test and to examine by mathematical modelling a hypothesis that SAR11 alphaproteobacteria and Prochlorococcus cyanobacteria numerically dominate the open ocean because of their photoheterotrophy. Using a combination of laboratory and oceanic cruise experiments the following objectives will be addressed: (i) to determine uptake rates of phosphate and amino acids as a function of light intensity and spectrum by the main planktonic prokaryotic groups, SAR11 and Prochlorococcus, and to relate these rates to cyanobacterial rates of CO2 fixation; (ii) to quantify mesoscale spatial and depth-related variations of group-specific rates of light-enhanced uptake of phosphate and amino acids within the euphotic zone, linking these variations in photoheterotrophy with population sizes and composition of the dominant groups in the North Atlantic subtropical gyre; (iii) to compare photoheterotrophic rates in the North Atlantic gyre with the ones in the Southern gyre and the Equatorial region, using light-enhanced amino acid uptake in order to ascertain the significance of photoheterotrophic use of light at the ocean scale. In order to meet the above objectives we will focus on experimental work in the open Atlantic Ocean combining isotopic tracer nutrient bioassays with flow cytometric sorting of bacterioplankton cells followed by ultra-sensitive radioassaying of cells, cell identification by fluorescence in situ hybridization and nano-scale secondary-ion mass spectrometry in conjunction with molecular identification of prokaryotic cells by halogen in situ hybridisation. Our overarching aim is to establish the input of solar energy into the microbial world of the open ocean beyond that used for CO2 fixation.

该提案的目的是找出光异养在开放海洋中的重要性-地球上最大的生态系统，对全球地球化学和气候具有深远的重要性。光异养原核生物利用光作为能量，但不能利用二氧化碳作为其唯一的碳源，因此利用环境中的有机分子来满足其碳需求。尽管在理解几种光合异养机制方面取得了相当大的进展，但太阳辐射在海洋浮游细菌代谢中的作用仍难以评估，尽管已经很明显，原核细胞的CO2固定可能只是其中的一部分。该项目提议通过数学建模实验测试和研究一种假设，即SAR 11 α变形菌和原绿球藻蓝藻因其光异养而在数量上占主导地位。利用实验室和海洋航行实验相结合的方法，将达到以下目的：（一）确定主要的浮游原核生物群体SAR 11和原绿球藻对磷酸盐和氨基酸的吸收率，作为光强度和光谱的函数，并将这些吸收率与蓝藻的CO2固定率联系起来;（ii）量化透光层内磷酸盐和氨基酸的光增强吸收的组特异性速率的中尺度空间和深度相关变化，将光异养的这些变化与北大西洋亚热带环流中的种群规模和优势种群的组成联系起来;（iii）利用光增强的氨基酸吸收，比较北大西洋环流与南大西洋环流和赤道区域的光异养率，以确定光异养利用在海洋尺度上的意义。为了实现上述目标，我们将集中在开放的大西洋的实验工作相结合的同位素示踪剂营养生物测定与流式细胞仪分选浮游细菌细胞，然后由超灵敏的放射性细胞分析，细胞识别荧光原位杂交和纳米级二次离子质谱结合分子鉴定的原核细胞卤素原位杂交。我们的首要目标是建立太阳能输入到开放海洋的微生物世界，而不是用于固定二氧化碳。