Dimensions: Collaborative Research: Functional Diversity of Microbial Trophic Guilds Defined Using Stable Isotope Ratios of Proteins

DNA测序技术的进步加快了物种和基因分布的发现步伐，特别是微生物。这种加速与将环境遗传学和分类多样性与这些生物的功能、资源利用和生态位联系起来的缓慢进展形成鲜明对比。本项目将开发一种新的同位素地球化学应用，并将其应用于生物化学海洋学领域，作为应对这些挑战的第一步。该项目的目标是将天然同位素比率数据与蛋白质组学相结合。不同的代谢过程产生不同比例的碳、氮、氢和硫的稳定同位素；通过测量特定蛋白质上的这些比率，这些天然同位素信号可以将生物地球化学过程（功能）归因于特定微生物（分类和遗传信息）。由于这是一种新颖的方法，该项目首先将寻求确定不同类型营养结构可能产生的自然同位素分类的基本原理。这将使用纯培养物来实现，然后将在分层湖的模型生态系统上进行测试。要回答的一个问题的例子是：在混合微生物群落中，生物遗传指纹的分布与群落的遗传多样性是如何关系的？更高的遗传多样性是否预示着更高的营养或喂养水平？这项研究将有助于发展营养行会和微生物生态系统依赖性的概念；这些概念在宏观生态学中得到了很好的发展，但对微生物多样性的理解还不够好。如果不更好地了解维持微生物功能和遗传多样性的原因，生态系统保护是不可能的。该项目的成功将为进一步了解非培养微生物在环境中的生理和生态作用带来许多应用。该项目有三位主要研究人员：一位同位素地球化学家、一位微生物生理学家和一位微生物生态学家——这是一个非常适合实现将地球化学与微生物多样性联系起来的跨学科目标的团队。计划的活动将培养一名博士后研究员，两名研究生和几名本科生暑期学生。通过额外的活动，如剑桥科学节和科学品脱，研究也将传达给公众。

Advancements in DNA sequencing technology have accelerated the pace of discovery of species and gene distributions, especially for microorganisms. This acceleration contrasts with slower progress in linking environmental genetics and taxonomic diversity to the function, resource utilization, and ecological niches of these organisms. This project will develop a novel application of isotope geochemistry and apply it in the field of biochemical oceanography as a first step toward tackling these challenges. The goal of the project is to combine natural isotope ratio data with proteomics. Different metabolic processes yield different ratios of the stable isotopes of carbon, nitrogen, hydrogen, and sulfur; and by measuring these ratios on specific proteins, these natural isotope signals can attribute biogeochemical processes (functions) to specific microbes (taxonomic and genetic information). Because this is a novel methodology, the project first will seek to identify the fundamental principles of natural isotopic sorting that could result from different types of trophic structure. This will be implemented using pure cultures and then will be tested on a model ecosystem from a stratified lake. An example of a question to be answered is: How does the distribution of organisms' genetic fingerprints in a mixed microbial community scale with the community's genetic diversity? Does higher genetic diversity predict more trophic, or feeding, levels?This research will help to develop a concept of trophic guilds and ecosystem dependence for microbes; such concepts are well developed in macro-ecology, but remain less well understood for microbial diversity. Ecosystem conservation is not possible without a better understanding of what maintains microbial functional and genetic diversity. The success of this project could lead to many further applications for understanding the physiological and ecological roles of uncultured microbes in the environment. The project has three principal investigators: an isotope geochemist, a microbial physiologist, and a microbial ecologist - a team well suited to achieve the interdisciplinary goal of linking geochemistry with microbial diversity. The proposed activities will educate a post-doctoral investigator, two graduate students, and several undergraduate summer students. Through additional activities such as The Cambridge Science Festival and Science by the Pint, the research also will be communicated to the general public.