Membrane vesicles produced by marine bacteria: origins, distributions, and functions

海洋细菌产生的膜囊泡：起源、分布和功能

• 批准号: 1356460
• 负责人: Sallie Chisholm
• 金额: $ 59.92万
• 依托单位: Massachusetts Institute of Technology
• 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: 2014-02-01 至 2019-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1356460&HistoricalAwards=false
• 关键词: Membrane; vesicles; produced; marine; bacteria

Overview: Some bacteria are known to release small amounts of their cell envelope in the form of tiny ( 200 nm diameter) spherical structures known as membrane vesicles. While the functions of these vesicles have been explored in pathogens, nothing is known about their abundance or roles in marine ecosystems. The investigators have recently demonstrated that Prochlorococcus, the numerically dominant photosynthetic cell in the world's oceans releases membrane vesicles continually during growth, and they have shown that these structures are indeed found in abundance in ocean samples. Bacterially produced membrane vesicles represent a major new feature of ocean ecosystems and could provide important clues about the network of interactions among microbes and their environment. Prochlorococcus vesicles contain diverse macromolecules, including lipids, proteins, and nucleic acids, suggesting that these structures could play many varied roles within marine microbial communities. The researchers will use the Prochlorococcus model system and the analysis of natural seawater samples from several field sites to address fundamental questions about the production and function of membrane vesicles in the oceans. The overarching questions motivating this study include: What environmental factors influence the rate of release of membrane vesicles by Prochlorococcus, and what can this tell us about the regulation of this process? How does vesicle abundance vary in different regions of the oceans? What DNA is found in vesicles from natural seawater samples? How does the vesicle "metagenome" compare to the bacterial metagenome, and what can this tell us about the diversity of organisms that release vesicles? What ecological roles might vesicles play in marine microbial ecosystems? Can they facilitate horizontal gene transfer? Can they act as a "decoy" to reduce phage predation?Intellectual Merit: Membrane vesicles represent a major new feature in ocean ecosystems. These discrete, organized structures may influence a number of biogeochemical processes, including horizontal gene transfer; moving small molecules, proteins or other macromolecules between cells; or serving as a source of fixed carbon for other bacteria. Yet we know nothing about them. This project will open this black box, and help us begin to understand the abundance and sources of membrane vesicles in the oceans, determine factors affecting their production by the numerically dominant photoautotroph Prochlorococcus, and explore aspects of their ecological roles in marine systems. With this research, the investigators will begin to establish a new area of study in marine microbial ecology that has the potential to alter current paradigms about the mechanisms through which microbes interact with both their biotic and abiotic environment.Broader Impacts: The investigators will take advantage of several avenues available at MIT to work with under-represented groups. These include: the MIT Summer Research Program, CONVERGE (a preview weekend); SEED (a Saturday education program); KEYs (a program for girls), and the MIT Edgerton Center which facilitates visits from local K-12 classes. The investigator is committed to communicating science to broad audiences. The PI has published two children's books on photosynthesis (Living Sunlight, Ocean Sunlight, Scholastic 2009, 2012; both received "best children's picture book" awards from AAAS), and is currently working on a third, on fossil fuels and climate, which will appear in 2014. This project will play a central role in the professional development of the post-doc(s) involved and data resulting from the proposed activity will be posted on public web sites, including the Prochlorococcus Portal (http://proportal.mit.edu/), and the Vesiclepedia database (http://www.microvesicles.org)

概述：已知一些细菌以微小（直径200纳米）球形结构（称为膜囊）的形式释放少量的细胞包膜。虽然这些囊泡的功能已经在病原体中进行了探索，但它们在海洋生态系统中的丰度或作用尚不清楚。研究人员最近证明，原绿球藻——世界海洋中数量上占主导地位的光合细胞——在生长过程中不断释放膜囊泡，他们已经证明，这些结构确实在海洋样本中大量存在。细菌产生的膜泡代表了海洋生态系统的一个重要新特征，可以为微生物与其环境之间的相互作用网络提供重要线索。原绿球藻囊泡含有多种大分子，包括脂质、蛋白质和核酸，表明这些结构可能在海洋微生物群落中发挥多种作用。研究人员将使用原绿球藻模型系统，并对来自几个实地地点的天然海水样本进行分析，以解决有关海洋中膜囊泡产生和功能的基本问题。推动这项研究的首要问题包括：什么环境因素影响原绿球藻释放膜囊泡的速度，这一过程的调控能告诉我们什么？海洋不同区域的囊泡丰度如何变化？在天然海水样本的囊泡中发现了什么DNA ？囊泡“宏基因组”如何与细菌宏基因组相比较，这能告诉我们释放囊泡的生物体的多样性吗？囊泡在海洋微生物生态系统中可能扮演什么生态角色？它们能促进水平基因转移吗？它们能作为“诱饵”来减少噬菌体的捕食吗？知识价值：膜泡代表了海洋生态系统的一个重要新特征。这些离散的、有组织的结构可能影响许多生物地球化学过程，包括水平基因转移；在细胞间移动小分子、蛋白质或其他大分子；或者作为其他细菌的固定碳的来源。然而，我们对它们一无所知。这个项目将打开这个黑盒子，帮助我们开始了解海洋中膜囊泡的丰度和来源，确定影响它们产生的因素，通过数量上占主导地位的光自养原绿球藻，并探索它们在海洋系统中的生态作用。通过这项研究，研究人员将开始在海洋微生物生态学中建立一个新的研究领域，该领域有可能改变目前关于微生物与生物和非生物环境相互作用机制的范式。更广泛的影响：研究人员将利用麻省理工学院提供的几种途径与代表性不足的群体合作。这些包括：麻省理工学院夏季研究项目，CONVERGE（周末预览）；SEED（周六教育项目）；KEYs（一个针对女孩的项目），以及麻省理工学院埃杰顿中心（MIT Edgerton Center），该中心为当地K-12班的学生提供便利。研究者致力于向广大受众传播科学。PI已经出版了两本关于光合作用的儿童书籍（Living Sunlight, Ocean Sunlight, Scholastic 2009, 2012；都获得了美国科学促进会颁发的“最佳儿童图画书”奖），目前正在编写第三本关于化石燃料和气候的书，将于2014年出版。这个项目将在相关博士后的专业发展中发挥核心作用，而计划活动的数据将公布在公共网站上，包括原绿球藻门户网站（http://proportal.mit.edu/）和Vesiclepedia数据库（http://www.microvesicles.org）。