Big River Microbiology: Bacterioplankton Diversity and Community Dynamics of the Six Largest Rivers in the Arctic Ocean Watershed

分子微生物生态学领域正在进入第二个时代，超越了简单的多样性调查，揭示了与曾经被认为只适用于“宏观”生物体的生态概念相一致的多样性组织模式。最近发现的同步性之间的独立的微生物群落，类群区域的关系，和细菌的特有性要求有凝聚力的，大规模的研究系统中的微生物多样性托管可比的微生物群落。淡水浮游细菌由于其相对有限的多样性和全球性分布，特别适用于这一目的。这些生物具有重要的生态意义，催化关键的生物地球化学反应，并作为水生微生物食物网的核心成员。多样性研究，主要是在湖泊中进行的，表明浮游细菌群落是动态的，响应于空间和时间的环境梯度变化的优势藻类。在河流中，由于水停留时间短，这种变化可能是迅速和极端的。这种敏感性使得河流浮游细菌成为确定微生物群落组成的环境控制的理想选择。不幸的是，我们对河流浮游细菌的多样性和动态知之甚少。这项工作将测试半球规模的模式的细菌多样性的特点和比较浮游细菌多样性的六条最大的河流在北冰洋流域，包括五个世界上最大的河流（奥布'，叶尼塞，莉娜，麦肯齐，育空地区，和科雷马河），并解释这些模式的物理，化学和生物测量的一个广泛的补充数据库。在合作伙伴组（泛北极河流运输的营养物质，有机物和悬浮沉积物），并部分资助与PI的新教师任命相关的“启动”资金，PI已经收集了高质量的DNA样本从这六条河流的口在2003年开始的4年期间。PARTNERS项目的总体目标是利用河水化学作为研究流入北冰洋的大陆径流的来源和归宿的工具。淡水浮游细菌可能是有用的河流特定的遗传示踪剂淡水在北冰洋，因为它们很容易区分海洋浮游细菌使用分子技术。首席研究员建议调查北极河流中丰富的，持久的，河流特异性的细菌细菌的种类，设计针对这些生物的PCR引物，并测试这些引物是否可以检测到北冰洋中高度稀释的淡水细菌。更广泛的影响。通过与合作伙伴的合作，该项目是一项多国奋进（美国，加拿大，俄罗斯），将加强国际交流。该项目还将增进对全球微生物多样性的了解，促进研究气候变化对北极的长期影响，并探索在海洋系统中使用遗传示踪剂。一名研究生将接受最先进的分子技术和生物信息学培训。新的发现将被纳入题为“水生微生物生态学”的研究生课程。数据、发现和DNA序列将张贴在伙伴关系项目网站上，供科学界下载。

The field of molecular microbial ecology is entering a second age, going beyond simple surveys of diversity and revealing organized patterns of diversity consistent with ecological concepts that were once thought only applicable to 'macroscopic' organisms. Recent discoveries of synchrony among independent microbial communities, taxa-area relationships, and bacterial endemism call for cohesive, large-scale studies of microbial diversity in systems hosting comparable microbial communities. Freshwater bacterioplankton are particularly useful for this purpose because of their relatively restricted diversity and their global distribution. These organisms are ecologically important, catalyzing critical biogeochemical reactions and serving as central members of aquatic microbial food webs. Diversity studies, conducted mainly in lakes, indicate bacterioplankton communities are dynamic, responding to spatial and temporal environmental gradients with shifts in dominant phylotypes. In rivers, such shifts can be rapid and extreme because of short water residence time. This sensitivity makes river bacterioplankton ideal for identifying environmental controls on the composition of microbial communities. Unfortunately, very little is known about the diversity and dynamics of river bacterioplankton. This work will test for hemisphere-scale patterns of bacterial diversity by characterizing and comparing the bacterioplankton diversity of the six largest rivers in the Arctic Ocean watershed, including five of the world's largest rivers (Ob', Yenisey, Lena, Mackenzie, Yukon, and Kolyma rivers), and interpreting these patterns by relating them to an extensive complementary database of physical, chemical and biological measurements. In collaboration with the PARTNERS group (Pan-Arctic River Transport of Nutrients, Organic Matter and Suspended Sediments), and partially funded with "start-up" funds associated with the PI's new faculty appointment, the PI has collected high quality DNA samples from the mouths of these six rivers over a 4 years period beginning in 2003. The overall goal of the PARTNERS project is to use river water chemistry as a tool to study the origins and fates of continental runoff to the Arctic Ocean. Freshwater bacterioplankton may be useful as river-specific genetic tracers freshwater in the Arctic Ocean as they are easily distinguishable from marine bacterioplankton using molecular techniques. The principal investigator proposes to survey Arctic Rivers for abundant, persistent, river-specific bacterial phylotypes, design PCR primers targeting these organisms, and test whether these primers can detect highly dilute freshwater bacteria in the Arctic Ocean. Broader Impacts. Through collaboration with PARTNERS, this project is a multi-national endeavor (USA, Canada, & Russia) that will strengthen international communication. It will also further the knowledge of global microbial diversity, contribute to research on the long-term impacts of climate change on the Arctic, and explore the use of genetic tracers in marine systems. One graduate student will be trained in state-of-the-art molecular techniques and bioinformatics. New discoveries will be incorporated into a graduate-level course entitled Aquatic Microbial Ecology. Data, discoveries and DNA sequences will be posted on the PARTNERS project website and made available for download by the scientific community.