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

蓝藻水华困扰着全球的湖泊和河流。这些有毒水华损害了湖泊生态系统的健康，威胁到周围社区的公共健康，并由于旅游业和渔业的减少而损害了当地经济。水华很难抗击，主要是因为促成水华形成微生物成功生长的因素还没有完全被了解。该项目将通过重点研究藻类如何与周围的细菌相互作用来获得和交换营养物质，特别是氮，从而为藻类水华的发生提供新的见解。通过实验操作、测量和生理模型的结合，这项工作将提供关于氮交换如何促进藻类水华的详细图景。这一结果将有助于环境管理者制定有效的缓解战略，以应对湖泊和河流中的有毒水华。实验将由詹姆斯·麦迪逊州立大学和莱特州立大学的本科生进行，大部分研究将在本科生课堂环境中进行，为学生在科学生涯早期提供出色的培训。研究人员还将与农村地区在家上学的学生合作，激励潜在的年轻科学家。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水化学并塑造生态系统功能。该项目的目标是对异养细菌和藻圈(浮游植物细胞周围的微环境)中的模式初级生产者之间的相互作用进行量化和建模，特别是氮交换。这项工作将：1)量化模型淡水蓝藻微囊藻对藻圈异养细菌的依赖；2)利用与单一异养伙伴的共培养实验，对微囊藻和特定藻圈伙伴之间的氮转移进行量化和建模，并对转录组进行分析，同时进行与氮有关的目标代谢物分析；以及3)通过跟踪和量化不同氮化合物通过共生藻圈联合体的流动，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.