Phylogenetic diversity of bacterioplankton in relation to distribution of cell-specific physiological properties and environmental conditions in an upwelling ecosystem

浮游细菌的系统发育多样性与上升生态系统中细胞特定生理特性和环境条件的分布有关

• 批准号: 0240785
• 负责人: Barry Sherr
• 金额: $ 39.02万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-03-15 至 2007-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0240785&HistoricalAwards=false
• 关键词: Phylogenetic; diversity; bacterioplankton; relation; distribution

Marine bacterioplankton are central and quantitatively significant components of marine ecosystems; their role looms large in determining the capacity of oceanic systems to sequester atmospheric CO2 into the deep ocean. Current models constructed to examine these questions consider marine bacterioplankton as a monolithically active compartment. This is in large part due to the lack of understanding regarding whether specific phylogenetic or physiologically identifiable groups of bacteria have distinct conditions for optimal growth, or whether diverse groups of bacterioplankton do in fact respond uniformly to changing environmental conditions, as the models assume. Flow cytometric enumeration of marine bacterioplankton using nucleic-acid specific stains has shown the routine presence of two distinct clusters of bacterial cells based on cell-specific nucleic acid (NA, i.e. DNA and RNA) content. Opposing ideas have been proposed concerning these distinct clusters of bacteria: 1) most bacterial activity is due to cells with higher nucleic acid content (high-NA), while lower nucleic acid content cells (low-NA) are either slow-growing or dead, or 2) both high-NA and low-NA cells have similar biomass-specific rates of activity. This research will focus on the high-NA and low-NA cells present in bacterial communities in the Oregon upwelling ecosystem. Two alternative hypotheses will be examined: Ho 1. High-NA and low-NA bacterial cells are composed of phylogenetically distinct bacterial assemblages that show differences in physiological activity. This would be the case if high NA and low-NA cells tend to fall into separate assemblages of cells that are adapted to different growth strategies. Ho 2- High-NA and low-NA cells tend to have similar phylogenetic compositions and similar biomass-specific rates of activity. The approach will involve flow cytometric enumeration and sorting of bacteria based on cell-specific nucleic acid or protein content. Sorted bacteria will be assayed for cell-specific activity via prior labeling with radioactive substrates, and assayed for phylogenetic diversity via PCR amplification of DNA extracted from sorted cells followed by DGGE analysis, sequencing of selected gel bands, and phylogenetic identification. At the same time, radiolabeled subsamples will be collected on filters and analyzed by combined microautoradiography and fluorescence in situ hybridization (FISH) using domain-specific probes, as well as more specific probes, in order to determine the relative contribution of substrate-active phylogenetic groups to total bacterial abundance. A main goal of the project is to put the results in ecological context, i.e. to relate variability in activity and diversity among high-NA and low-NA bacterioplankton to environmental parameters likely to affect the growth of marine bacteria (e.g. potential bottom-up controls such as phytoplankton biomass and riverine DOC influx). Intellectual merit: This research project will address the linkages between physiological and phylogenetic diversity in marine bacterioplankton, and how such linkages might affect bacterial processing of organic matter in marine systems. The results would be a significant step in understanding the role of specific phylogenetic components of the bacterioplankton community in global biogeochemical cycles and carbon flux. Broader impacts: This project will support the Ph.D. thesis research of a female graduate student and provide the student with post-doctoral training; it will also enhance the teaching efforts of the P.I..s and support the common use Flow Cytometry Facility and molecular genetics capabilities in the College of Oceanography and Atmospheric Sciences.

海洋浮游细菌是海洋生态系统的重要组成部分，在确定海洋系统将大气中的二氧化碳封存到深海的能力方面，它们的作用举足轻重。 目前构建的模型来研究这些问题，认为海洋浮游细菌作为一个整体的积极车厢。这在很大程度上是由于缺乏了解是否特定的系统发育或生理上可识别的细菌群体有不同的条件，最佳的生长，或是否不同群体的浮游细菌实际上一致地响应不断变化的环境条件，模型假设。使用核酸特异性染色剂的海洋浮游细菌的流式细胞计数显示了基于细胞特异性核酸（NA，即DNA和RNA）含量的两个不同细菌细胞簇的常规存在。关于这些不同的细菌簇，已经提出了相反的想法：1）大多数细菌活性是由于具有较高核酸含量（高NA）的细胞，而较低核酸含量的细胞（低NA）生长缓慢或死亡，或者2）高NA和低NA细胞具有相似的生物量特异性活性速率。这项研究将集中在高NA和低NA细胞存在于细菌群落中的俄勒冈州上升流生态系统。两个备选假设将被检查：Ho 1。高NA和低NA细菌细胞由在生理活性上显示差异的遗传学上不同的细菌集合体组成。如果高NA和低NA细胞倾向于落入适应不同生长策略的细胞的单独集合体，则会出现这种情况。 Ho 2-高NA和低NA细胞往往具有相似的系统发育组成和相似的生物量特异性活性率。该方法将涉及基于细胞特异性核酸或蛋白质含量的流式细胞计数和细菌分选。将通过事先用放射性底物标记来测定分选的细菌的细胞特异性活性，并通过PCR扩增从分选的细胞中提取的DNA，然后进行DGGE分析、选定凝胶条带测序和系统发育鉴定来测定系统发育多样性。同时，将在过滤器上收集放射性标记的子样品，并使用结构域特异性探针以及更特异的探针通过显微放射自显影和荧光原位杂交（FISH）组合进行分析，以确定底物活性系统发育组对总细菌丰度的相对贡献。该项目的一个主要目标是将结果置于生态背景下，即将高NA和低NA浮游细菌之间的活动和多样性的变化与可能影响海洋细菌生长的环境参数（例如，潜在的自下而上的控制，如浮游植物生物量和河流DOC流入量）联系起来。智力优点：本研究项目将探讨海洋浮游细菌生理和系统发育多样性之间的联系，以及这种联系如何影响海洋系统中细菌对有机物的处理。这一结果将是理解浮游细菌群落特定系统发育组分在全球生态地球化学循环和碳通量中的作用的重要一步。 更广泛的影响：该项目将支持博士学位。该项目将帮助一名女研究生进行论文研究，并为该学生提供博士后培训;它还将加强私人研究所的教学工作。支持海洋学和大气科学学院的通用流式细胞仪和分子遗传学能力。