Collaborative Research: Linking microbial diversity, gene expression, and the transformation of terrestrial organic matter in major U.S. rivers

合作研究：将美国主要河流的微生物多样性、基因表达和陆地有机质的转化联系起来

• 批准号: 1457794
• 负责人: Byron Crump
• 金额: $ 82.6万
• 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: 2015
• 资助国家: 美国
• 起止时间: 2015-05-01 至 2020-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1457794&HistoricalAwards=false
• 关键词: Collaborative; Research; Linking; microbial; diversity

Rivers and streams are the major conduits for transporting of Earth's carbon from the land to the oceans. Much of the carbon is in a dissolved organic form, and it serves as food for aquatic microorganisms. The challenge is that the chemical diversity of dissolved organic carbon is very great, and the genetic diversity of aquatic microbes is also immense. Accordingly, this project will use state-of-the art genomic methods to study the diversity and specific functions of these microorganisms. The results will fill a critical gap in understanding the specific metabolic capabilities of these microbes and how they carry out the key ecosystem function of transforming and metabolizing highly complex, riverborne dissolved organic carbon. The data that will be collected are important for predicting the impacts of land-use change, nutrient use, and shifting climate on freshwater quality across the USA. The research involves a collaboration with the Yale Peabody Museum Evolution program for inner-city New Haven high-school students to train interns and develop an interactive museum exhibit on U.S. rivers. The project will also train a postdoctoral researcher, and undergraduate and graduate students, including members of underrepresented groups in science.The goal of the project is to describe interactions and feedbacks between watershed diversity, microbial functional diversity, and dissolved organic matter (DOM) chemistry in 36 large U.S. rivers, and to experimentally link gene expression with DOM degradation in five of them (the Altamaha, Columbia, Mississippi, St. Lawrence and Yukon). River sampling will be conducted in collaboration with a U.S. Geological Survey stream network. This research will address the concept that microbial genetic mechanisms in river ecosystems are closely linked to climate and landscape features that control river environmental conditions, particularly DOM quality. This concept implies that microbial function is shaped by DOM composition, climate, and river chemistry. These shaping forces alter the functional genetic capabilities required for competitive success within riverine microbial communities, and, thus, drive shifts in functional gene expression and phylogenetic composition, that, in turn, increase the efficiency of DOM metabolism and biogeochemical processes. Three hypotheses are to be tested: (1) the functional genetic composition and gene expression patterns of riverine microbial communities are correlated with the composition of riverine DOM; (2) community gene expression patterns vary predictably in response to shifts in the available forms of DOM; and, (3) the composition of riverine bacterial communities correlates with the composition of riverine DOM over space and time, and varies with watershed-specific climatic factors. The first hypothesis will be addressed with an empirical study of microbial community gene content (metagenomics), gene expression (metatranscriptomics), and DOM diversity (high-resolution analytical chemistry) during four seasons in five rivers that encompass a broad range of DOM composition. The second hypothesis will be addressed with an experimental study to identify active organisms and genes expressed by freshwater microbial metabolism. The third hypothesis will be addressed with an empirical study of microbes, DOM, and river chemistry in 36 major U.S. rivers. Statistical approaches being developed through a Microsoft-sponsored international working group (BioGeoChemistry Data System) will be applied to link microbial and DOM data.

河流和溪流是将地球上的碳从陆地输送到海洋的主要渠道。大部分碳以溶解的有机形式存在，是水生微生物的食物。挑战在于，溶解有机碳的化学多样性非常大，水生微生物的遗传多样性也是巨大的。因此，该项目将使用最先进的基因组方法来研究这些微生物的多样性和特定功能。这些结果将填补在了解这些微生物的特定代谢能力以及它们如何执行转化和代谢高度复杂的河边溶解有机碳的关键生态系统功能方面的一个关键空白。将收集的数据对于预测土地利用变化、养分使用和气候变化对整个美国淡水质量的影响非常重要。这项研究涉及与耶鲁皮博迪博物馆进化计划合作，为纽黑文市中心的高中生培训实习生，并开发关于美国河流的互动博物馆展览。该项目还将培训一名博士后研究员、本科生和研究生，包括科学中代表性不足的群体的成员。该项目的目标是描述美国36条大河的流域多样性、微生物功能多样性和溶解有机物(DOM)化学之间的相互作用和反馈，并在其中五条河流(阿尔塔马哈、哥伦比亚、密西西比、圣劳伦斯和育空)试验将基因表达与DOM降解联系起来。河流采样将与美国地质调查局河流网络合作进行。这项研究将阐述这样一个概念，即河流生态系统中的微生物遗传机制与控制河流环境条件的气候和景观特征密切相关，特别是DOM质量。这一概念意味着微生物的功能是由DOM组成、气候和河流化学决定的。这些塑造力量改变了在河流微生物群落中竞争取胜所需的功能遗传能力，从而推动功能基因表达和系统发育组成的变化，这反过来又提高了DOM代谢和生物地球化学过程的效率。需要检验三个假设：(1)河流微生物群落的功能遗传组成和基因表达模式与河流DOM的组成相关；(2)群落基因表达模式随可用DOM形式的变化而发生可预测的变化；(3)河流细菌群落的组成与河流DOM的组成在空间和时间上相关，并随流域特有的气候因素而变化。第一个假设将通过五条河流中微生物群落基因含量(元基因组学)、基因表达(元转录组学)和DOM多样性(高分辨率分析化学)的实证研究来解决，这些河流涵盖了DOM组成的广泛范围。第二个假设将通过实验研究来确定活跃的生物体和淡水微生物新陈代谢表达的基因。第三个假设将通过对美国36条主要河流的微生物、DOM和河流化学的实证研究来解决。通过微软赞助的国际工作组(生物地球化学数据系统)开发的统计方法将用于将微生物数据和DOM数据联系起来。