Collaborative Research: RUI: Examining the role of nitrogen exchange in the formation of algal blooms

蓝藻的大量繁殖困扰着全球的湖泊和河流。这些有毒的水华破坏了湖泊生态系统的健康，威胁到周围社区的公众健康，并因旅游业和渔业的减少而损害当地经济。水华很难控制，主要是因为促成水华形成微生物成功生长的因素尚未完全了解。该项目将通过关注藻类如何与周围细菌相互作用以获取和交换营养物质，特别是氮，为藻华的发生提供新的见解。通过实验操作、测量和生理建模的结合，这项工作将提供氮交换如何促进藻华的详细图景。这一结果将有助于环境管理者制定有效的缓解战略，以对抗湖泊和河流中的有毒水华。实验将由詹姆斯麦迪逊州立大学和赖特州立大学的本科生进行，大部分研究将在本科生的课堂环境中进行，为学生早期的科学生涯提供良好的训练。研究人员还将与农村地区在家上学的学生合作，激励有潜力的年轻科学家。在水生系统中，初级生产者和异养细菌之间的相互作用改变了水的化学性质并塑造了生态系统的功能。该项目的目标是量化和模拟异养细菌与藻圈（浮游植物细胞周围的微环境）中模型初级生产者之间的相互作用，特别是氮交换。本工作将：1)量化淡水蓝藻微囊藻对藻圈异养细菌的依赖；2)通过与单个异养伴侣共培养实验，量化和模拟微囊藻与特定藻球伙伴之间的氮转移，并在进行靶向氮相关代谢物分析的同时分析转录组；3)通过追踪和量化不同氮化合物在共生藻圈联合体中的流动，将氮转移模型扩展到整个藻圈联合体。

Cyanobacterial algal blooms plague lakes and rivers across the globe. These toxic blooms damage the health of lake ecosystems, threaten the public health of surrounding communities, and harm local economies due a reduction in tourism and fishing industries. Blooms are hard to combat, mainly because the factors that contribute to the successful growth of bloom-forming microbes are not yet fully understood. This project will provide new insight into how algal blooms occur by focusing on how the algae interact with surrounding bacteria to obtain and exchange the nutrients, especially nitrogen, that allow the blooms to occur. Through a combination of experimental manipulation, measurements, and physiological modeling, the work will provide a detailed picture of how nitrogen exchange promotes algal blooms. This results will help environmental managers develop effective mitigation strategies to combat toxic blooms in lakes and rivers. Experiments will be conducted by undergraduate students at James Madison and Wright State Universities, and much of the research will take place in an undergraduate classroom setting, providing excellent training for students early in their science careers. The researchers will also work with homeschooled students in rural areas, inspiring potential young scientists.In aquatic systems, interactions between primary producers and heterotrophic bacteria alter water chemistry and shape ecosystem function. The goal of this project is to quantify and model interactions, specifically nitrogen exchange, between heterotrophic bacteria and a model primary producer in the phycosphere (the microenvironment surrounding a phytoplankton cell). This work will: 1) quantify the reliance of the model freshwater cyanobacterium Microcystis on the heterotrophic bacteria in the phycosphere; 2) quantify and model the transfer of nitrogen between Microcystis and specific phycosphere partners, using co-culture experiments with a single heterotrophic partner, and profile the transcriptome while simultaneously performing targeted nitrogen-related metabolite analysis; and 3) expand the model of nitrogen transfer to the entire phycosphere consortium by tracing and quantifying the flow of different nitrogen compounds through the symbiotic phycosphere consortium.