Collaborative Research: Biocomplexity of Aquatic Microbial Systems: Relating Diversity of Microorganisms to Ecosystem Function

生物复杂性：合作研究：水生微生物系统的生物复杂性--微生物多样性与生态系统功能的关系元素的微生物地球化学循环调节一个动态环境，其中不同元素的循环通过微生物的生理学联系在一起。虽然可以通过物理/化学方法来测量和模拟净转化，但这些方法必然依赖于对所涉及的各种官能团（行业协会）的作用和调节的粗略简化。分子微生物生态学的最新进展表明，微生物世界在每一个层次上都包含着巨大的多样性和复杂性：单一生物体内功能基因的冗余和重复;不同生物体内编码相同过程的功能基因之间的分子多样性;在单一群落内显然参与相同生物地球化学功能的不同生物之间的巨大遗传多样性;不同群落的物种组成差异很大，但显然表现同样出色。该项目的目标是在一系列生物和生态尺度上研究微生物群落的复杂性与物理/化学环境之间的功能关系。以前，这种分析在技术上受到限制，因为不能同时测定大量基因和突变类型的大量样品。利用基因阵列技术，研究人员将能够检测自然系统中功能基因的分布和差异表达。这项研究的结果将构成DNA芯片技术应用于“外来”基因表达的第一步（即，不具有生物医学重要性）过程和环境中的生物体。基因阵列，沿着一套完整的生态系统过程测量，将被部署沿着一条横断面，该横断面跨越从切萨皮克湾的内陆沃茨到马尾藻海的富营养-贫营养梯度。实验和功能基因研究将集中在碳和氮循环的关键转换（C固定，N固定，硝化，反硝化，尿素同化）。利用地球化学数据和示踪剂实验，从生态系统功能的角度解释公会的多样性。除了旨在调查和剖析自然系统的实地研究外，合作科学家小组还将利用中型生态系统进行扰动实验。这些实验的目的是确定微生物物种多样性如何影响生态系统内的主要能量和营养流，并评估与负责主要氮和碳途径的微生物行会内冗余变化相关的稳定或不稳定程度。

BIOCOMPLEXITY: Collaborative Research: Biocomplexity of aquatic microbial systems -- relating diversity of microorganisms to ecosystem functionMicrobial biogeochemical cycling of the elements regulates a dynamic environment in which the cycles of different elements are linked through the physiology of microorganisms. While a certain degree of understanding can be gained through physical/chemical approaches to measurement and modeling of the net transformations, these approaches necessarily rely on gross simplifications about the role and regulation of the various functional groups (guilds) involved. Recent advances in molecular microbial ecology have shown the microbial world to contain immense diversity and complexity at every level: redundancy and duplication of functional genes within a single organism; molecular diversity among functional genes that encode the same process in different organisms; large genetic diversity among different organisms apparently engaged in the same biogeochemical function within single communities; great variability in the species composition of different communities that apparently perform equally well. The goal of this project is to investigate the functional relationship between complexity in microbial communities and the physical/chemical environment at a range of biological and ecological scales. Previously, such analysis was technologically limited by the inability to assay large numbers of samples simultaneously for a large number of genes and phylotypes. Using gene array technology, the researchers will be able to detect the distribution and differential expression of functional genes in natural systems. The results of this study will constitute the first step towards application of DNA chip technology for gene expression of "exotic" (i.e., not of biomedical importance) processes and organisms in the environment. The gene arrays, along with a full suite of ecosystem process measurements, will be deployed along a transect that spans the eutrophic - oligotrophic gradient from the inland waters of the Chesapeake Bay out to the Sargasso Sea. Experiments and functional gene studies will focus on key transformations in the carbon and nitrogen cycles (C fixation, N fixation, nitrification, denitrification, urea assimilation). The diversity of guilds will be interpreted in terms of ecosystem function, assessed using geochemical data and tracer experiments. In addition to field studies designed to investigate and dissect the natural system, the group of collaborating scientists will also perform perturbation experiments using mesocosms. The goal of these experiments is to determine how microbial species diversity affects the major energy and nutrient flows within ecosystems, and to assess the degree of stability or instability associated with changes in redundancy within guilds of microorganisms responsible for major nitrogen and carbon pathways.