Biocomplexity: The Roles of Resources, Competition, and Predation in Microbial Degradation of Organic Matter

生物复杂性：资源、竞争和捕食在有机物微生物降解中的作用

• 批准号: 0120453
• 负责人: Gary Taghon
• 金额: $ 200万
• 依托单位: Rutgers University New Brunswick
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-10-15 至 2007-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0120453&HistoricalAwards=false
• 关键词: Biocomplexity; Roles; Resources; Competition; Predation

ABSTRACTOCE-0120610Bacteria play crucial roles in cycling of elements and thus the functioning of the biosphere. We know a great deal about the metabolic diversity of bacteria, and the pathways of the reactions they perform. Outside of simple laboratory systems, however, we cannot predict with any certainty the rates at which bacteria grow, metabolize, and mineralize organic matter. This project is about understanding, at a mechanistic and thus quantitative level, what affects the activity of bacteria in nature. While initially the problem seems straightforward, the investigators believe that its solution has been elusive because there are complex processes involved. This complexity exists over several levels of biological organization (individual, population, community), and in the microscale spatial heterogeneity of the environments in which bacteria function. The ultimate goal of this study is to develop, and test, a model that will predict the rates of organic matter cycling in natural systems. Such a model must include the physical and chemical factors controlling the availability of resources (reactants) to bacteria, interactions (potentially competitive) among different bacterial populations, and interactions among bacteria and their predators. The shorter-term goal, and the explicit goal of this project, is to focus on one type of environment - estuarine sediments - and one category of organic matter - polycyclic aromatic hydrocarbons (PAHs) in a background of natural organic matter. The approach centers on a tight coupling between modeling and empiricism, since it is our belief that models and experiments lead to new, useful knowledge only when there is a steady interaction. The model we will develop considers both bottom-up (e.g., resource availability) and to-down (e.g., predation) controls on bacterial activity. Estuarine sediment will be used as the environmental matrix for modeling and experimental testing inasmuch as these sediments are inherently complex and heterogeneous due to their widely varied chemical and physical properties, the mixtures of organic and inorganic constituents of which they are composed, and the simultaneous occurrence of chemical, physical, and biological processes. Bicyclic and polycyclic aromatic hydrocarbons (PAHs) will be chosen as a type of reactant that is used by only certain types of bacteria in the system. Thus, the time rate of change in PAHs will be used as a barometer of the activity of some members of the community. This will provide a sensitive and specific comparison of model predictions and experimental data. Models will be structured to account for variability in properties of the biological and abiotic components. The framework of the models will include spatial heterogeneity in sediment properties, population dynamics including competition and predation, nutrient and PAH mass transfer, and molecular dynamic simulations. Complexity will be added incrementally, as indicated by closely coupling model predictions with experimental results. The expertise of the group assembled to conduct the proposed research encompasses ecology, engineering, environmental geochemistry, and microbiology. Educational and training opportunities, on a variety of levels, will be built into this research. Specifically, the project will include mechanisms to enhance coursework in both undergraduate and graduate programs in environmental technology and engineering education; to broaden student research training that will explore dynamic interactions within and among environmental systems and will be directed by a multidisciplinary team of faculty investigators; and to provide enrichment opportunities for in-service teachers of science courses in grades 5-8 through a partners-in-learning program.

细菌在元素的循环中起着至关重要的作用，从而影响生物圈的功能。我们对细菌的新陈代谢多样性以及它们进行反应的途径了解很多。然而，在简单的实验室系统之外，我们无法确切地预测细菌生长、代谢和矿化有机物的速度。这个项目是关于从机械和定量的层面上理解影响自然界中细菌活动的因素。虽然最初这个问题看起来很简单，但调查人员认为，由于涉及复杂的过程，它的解决方案一直难以捉摸。这种复杂性存在于生物组织(个体、种群、群落)的几个层面上，以及细菌发挥作用的环境的微观空间异质性中。这项研究的最终目标是开发和测试一个预测自然系统中有机物质循环速率的模型。这样的模型必须包括控制细菌资源(反应物)可用性的物理和化学因素，不同细菌种群之间的相互作用(潜在竞争)，以及细菌和它们的捕食者之间的相互作用。短期目标，也是该项目的明确目标，是以天然有机物质为背景，重点研究一类环境--河口沉积物--和一类有机物质--多环芳烃。这种方法的核心是建模和经验主义之间的紧密耦合，因为我们相信，只有当存在稳定的交互作用时，模型和实验才会产生新的有用的知识。我们将开发的模型考虑了自下而上(例如，资源可用性)和自下而上(例如，捕食)对细菌活动的控制。河口沉积物将被用作模拟和实验测试的环境基质，因为这些沉积物本身就是复杂和非均质的，因为它们的化学和物理性质千差万别，它们是由有机和无机成分组成的混合物，以及同时发生的化学、物理和生物过程。双环和多环芳香烃(PAHs)将被选为仅供系统中某些类型的细菌使用的反应物类型。因此，多环芳烃的时间变化率将被用作社区某些成员活动的晴雨表。这将提供模型预测和实验数据的敏感和具体的比较。将构建模型，以考虑生物和非生物成分属性的可变性。模型的框架将包括沉积物性质的空间异质性、包括竞争和捕食的种群动力学、营养物质和多环芳烃的传质以及分子动力学模拟。复杂性将逐渐增加，正如模型预测与实验结果紧密结合所表明的那样。聚集起来进行这项拟议研究的小组的专业知识包括生态学、工程学、环境地球化学和微生物学。不同层次的教育和培训机会将纳入这项研究。具体地说，该项目将包括加强环境技术和工程教育本科生和研究生课程的机制；扩大学生研究培训的范围，探索环境系统内部和之间的动态互动，并将由教师研究人员组成的多学科团队指导；通过学习伙伴计划为5-8年级的科学课程的在职教师提供丰富的机会。