EAGER: Competition and interactions among predators of bacteria in microbial loop dynamics

美国国家科学基金会使用探索性研究的早期概念拨款（EAGER）资助机制来支持在未经测试但具有潜在变革性的研究思路或方法的早期阶段的探索性工作。这个EAGER项目是由于Dear Colleague Letter NSF 16-080邀请来自历史上的黑人学院和大学的申请者提交提案，以加强该机构教师的研究能力而获得的。佛罗里达农业和机械大学的这个项目旨在研究海洋水域中掠食性细菌——类蛭弧菌生物（BALOs）的生态作用。项目结果不仅可以揭示细菌捕食者之间的相互作用，而且可以揭示各种环境因素下捕食者与被捕食细菌之间的相互作用。本研究的科学目标是：研究病毒、卵形盐杆菌和异养原生生物如何相互影响以降低细菌丰度；量化所有三种死亡机制对细菌损失的相对比例；确定环境对原生生物、病毒和卵状盐杆菌捕食活动的影响；并模拟捕食者和猎物的种群动态。实现这些目标的方法是测量病毒、异养原生生物和卵形盐杆菌在实验室微观环境和实地研究中对细菌死亡率的损失率。这种方法的新颖性和创新性在于，虽然许多这些组成部分已被独立检查，但这将是第一次对这个复杂系统的死亡率进行定量划分。这个创新的早期概念探索性研究项目的预期高回报是变革性的结果，它极大地增加了对三营养浮游生物相互作用的理解，这种相互作用通过微生物环显着影响海洋碳和营养物质的生物地球化学通量，并揭示了盐杆菌是主要的细菌捕食者。

The National Science Foundation uses the Early-concept Grants for Exploratory Research (EAGER) funding mechanism to support exploratory work in its early stages on untested, but potentially transformative, research ideas or approaches. This EAGER project was awarded as a result of the invitation in the Dear Colleague Letter NSF 16-080 to proposers from Historically Black Colleges and Universities to submit proposals that would strengthen research capacity of faculty at the institution. The project at Florida Agricultural and Mechanical University aims to study the ecological role of predatory bacteria, Bdellovibrio-like organisms (BALOs), in marine waters. The project outcome can reveal interactions not only amongst the bacterial predators but also among the predators and their prey bacteria under various environmental factors. The scientific objectives of this study are to: investigate how viruses, Halobacteriovorax, and heterotrophic protists effect one another in decreasing bacterial abundance; quantify the relative proportion of all three mortality mechanisms on bacterial loss; determine environmental effects on predatory activities of protists, viruses, and Halobacteriovorax; and model population dynamics of predators and prey. The approach to accomplishing these objectives is to measure loss rates of a virus, heterotrophic protist, and a Halobacteriovorax on the mortality of bacteria in laboratory microcosms and field studies. The novelty and innovativeness of this approach is that while many of these components have been examined independently, this would be the first time that mortality is quantitatively partitioned for this complex system. The expected high-payoff from this innovative Early-Concept for Exploratory Research project is transformative results that dramatically increase understanding of tri-trophic planktonic interactions that significantly influence oceanic biogeochemical fluxes of carbon and nutrients through the microbial loop and reveal Halobacteriovorax as a major bacterial predator.