MO: Collaborative Research: Transitions in the Surface Layer and the Role of Vertically Stratified Microbial Communities in the Carbon Cycle- An Oceanic Microbial Observatory

MO：合作研究：表层转变和垂直分层微生物群落在碳循环中的作用 - 海洋微生物观测站

• 批准号: 0802004
• 负责人: Stephen Giovannoni
• 金额: $ 47.92万
• 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: 2008
• 资助国家: 美国
• 起止时间: 2008-08-15 至 2013-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0802004&HistoricalAwards=false
• 关键词: MO; Collaborative; Research; Transitions; Surface

The focus of this proposal is the role of bacterioplankton microbial community stratification in the ocean carbon cycle. Complex biological, chemical and physical processes control the efficiency of carbon transfer from the euphotic zone ocean to the deep sea, where sequestration is a possibility. Most organic carbon exported from the euphotic zone never leaves the surface 500 m, with approximately ninety percent of the exported organic matter being remineralized in the mesopelagic zone (140 - 1000 m). Microbial communities are vertically stratified in the oceans, particularly in the surface layer (0-300 m), which spans the region of deep mixing events and transition from the euphotic zone to the upper mesopelagic - the region of highest carbon remineralization activity. The premise of this proposal is that stratified bacterioplankton clades engage in specialized biogeochemical activities that can be identified by integrated oceanographic and microbiological approaches. Specifically, the objective of this proposal is to assess if the mesopelagic microbial community rely on diagenetically altered organic matter and subcellular fragments that are produced by microbial processes in the euphotic zone and delivered into the upper mesopelagic by sinking or mixing. In past efforts this microbial observatory had greater success cultivating members of the euphotic zone microbial community, and revealed an unanticipated growth requirement for reduced sulfur compounds in alphaproteobacteria of the SAR11 clade. Genomic information showed that intense competition for substrates imposes trade-offs on bacterioplankton - there are regions of N dimensional nutrient space where specialists win. We postulate that specific growth requirements may explain some the regular spatial and temporal patterns that have been observed in upper mesopelagic bacterioplankton communities, and the difficulties of culturing some of these organisms.The specific objectives of this project are: 1) to produce 13C and 15N labeled subcellular (e.g., soluble, cell wall, and membrane) and DOM fractions from photosynthetic plankton cultures and use stable isotope probing to identify specific clades in the surface and upper mesopelagic microbial community that assimilate fractions of varying composition and lability. 2) to use fluorescence in situ hybridization approaches to monitor temporal and spatial variability of specific microbial populations identified from the SIP and HTC experiments. To increase resolution we will use CARD-FISH protocols. 3) to measure the proteomes of bacterioplankton communities to identify highly translated genes in the surface layer and upper mesopelagic, and community responses to seasonal nutrient limitation. 4) and, to cultivate these organisms via high throughput culturing (HTC) by pursuing the hypothesis that they require specific nutrient factors and/or diagenetically altered organic substrates. Complete genome sequences from key organisms will be sought and used as queries to study patterns of natural variation in genes and populations that have been associated with biogeochemically important functions.This project will make cultures of novel bacterioplankton and genome sequences available to the scientific community. Findings from this research may be used directly in foodweb and ocean carbon cycle models. The educational component of this research brings microbial oceanography training to students from many disciplines, through a summer course, and specialized training to graduate and undergraduate students involved directly in research.

该提案的重点是浮游细菌微生物群落分层在海洋碳循环中的作用。复杂的生物、化学和物理过程控制着碳从真光层海洋转移到深海的效率，而在深海，固碳是可能的。从真光层输出的大多数有机碳从未离开500米的表面，大约90%的输出有机物质在中层（140 - 1000米）被矿化。微生物群落在海洋中垂直分层，特别是在表层（0-300米），这一层跨越了深层混合活动区域和从真光层到中上层的过渡区域-这是碳矿化活动最高的区域。这一建议的前提是，分层浮游细菌分支从事专门的生物地球化学活动，可以确定的综合海洋学和微生物的方法。具体而言，本提案的目的是评估中层微生物群落是否依赖于真光层微生物过程产生的成岩改变的有机物和亚细胞碎片，并通过下沉或混合进入上层中层。在过去的努力中，这个微生物观测站在培养真光层微生物群落的成员方面取得了更大的成功，并揭示了SAR 11进化枝的alphaproteobacteria中对还原硫化合物的意外生长需求。基因组信息表明，激烈的竞争基板上的浮游细菌的权衡-有N维营养空间的专家获胜的区域。本项目的具体目标是：1）制备13 C和15 N标记的亚细胞（例如，13 C和15 N标记的亚细胞），并将其转化为13 C和15 N标记的亚细胞（例如，15 N标记的亚细胞），然后将其转化为15 N标记的亚细胞（例如，15 N标记的亚细胞），并将其转化为15 N标记的亚细胞（例如，15 N标记的亚细胞）。可溶性的，细胞壁和膜）和DOM组分从光合浮游生物培养，并使用稳定同位素探测，以确定特定的分支在表面和上层中层微生物群落同化不同的组成和不稳定性的部分。2)使用荧光原位杂交方法来监测从SIP和HTC实验中鉴定的特定微生物种群的时间和空间变异性。为了提高分辨率，我们将使用CARD-FISH协议。3)测量浮游细菌群落的蛋白质组，以确定表层和中上层高度翻译的基因，以及群落对季节性营养限制的反应。4)以及通过高通量培养（HTC）培养这些生物体，所述高通量培养是通过追求它们需要特定营养因子和/或成岩改变的有机基质的假设进行的。将寻找关键生物的完整基因组序列，并将其用作查询，以研究与生物地球化学重要功能有关的基因和种群的自然变异模式，该项目将为科学界提供新的浮游细菌培养物和基因组序列。这项研究的结果可以直接用于食物网和海洋碳循环模型。这项研究的教育部分通过暑期课程为许多学科的学生提供微生物海洋学培训，并为直接参与研究的研究生和本科生提供专门培训。