URoL:EN: Understanding the rule of life facilitating the proliferation of toxic cyanobacterial benthic mats in flowing freshwaters

河流和溪流占地球上可用淡水总量的不到1%，但具有巨大的生态和社会意义。近年来，形成生物膜的有毒蓝藻，俗称底栖有害蓝藻水华，在许多河流和溪流中广泛存在。这些蓝藻产生毒素作为次级代谢产物，当食用时对人类和其他动物有害。来自底栖蓝藻属微鞘藻（原席藻属）的物种可以在流动的淡水中形成厚垫，从而在空间和时间模式中产生难以预测的蓝藻毒素。微鞘藻底栖垫已成为普遍和表现出有趣的新兴行为。微鞘藻的有毒菌株与其无毒对应物和其他蓝藻共存。有毒微鞘藻的许多代谢途径与其他蓝藻的常规途径不同。通过使用一套基因组和建模工具的实验室和现场规模的测试相结合，该项目旨在了解Microcoleus的时空动态以及控制Microcoleus属的动态和紧急行为导致有毒底栖垫的生命规则。预计这些结果将为淡水河流中底栖有毒垫的生态科学开辟新的机会，并适用于减轻蓝藻水华。该项目将扩大参与，促进环境生物学、数据科学、生态工程、化学、数学建模和计算机科学方面的学生培训，重点是培训代表性不足群体的学生。 尽管最近的研究结果表明，有毒和无毒菌株的微鞘藻协同其代谢的努力，以促进彼此在殖民化，如何营养浓度，河床类型，和其他环境因素中发挥作用的新兴规则的生活管理的殖民化和毒素生产微鞘藻没有很好地理解。因此，该项目旨在研究的生活规则是微鞘藻如何通过与其无毒对应物和底栖垫中其他共存细菌的相互作用形成垫和产生毒素。该项目将研究（1）垫内物种的相互作用和生态地球化学条件如何促进微鞘藻在低营养溪流中的生长和毒素产生，（2）分子机制（例如，基因表达水平），毒性非异细胞（例如，微鞘藻）和异细胞蓝细菌（能够固定大气氮气的固氮生物，例如，鱼腥藻）在氮和/或磷缺乏的流动沃茨中繁盛，（三）开发模型来预测河流尺度上有毒微鞘藻的发生和动态，并量化蓝藻群落动态和非生物环境条件如何在生长季节驱动底栖蓝藻和毒素生产。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准。

Rivers and streams make up less than 1 % of the total surface freshwater available on earth, but are of enormous ecological and societal significance. Recently, biofilm forming toxic cyanobacteria, commonly known as benthic harmful cyanobacterial blooms, have become widespread in many rivers and streams. These cyanobacteria produce toxins as secondary metabolites which are harmful to humans and other animals when consumed. Species from the benthic cyanobacterial genus Microcoleus (formerly Phormidium) can form thick mats in flowing freshwaters which produce cyanotoxins in spatial and temporal patterns that are challenging to predict. Microcoleus benthic mats have become widespread and exhibit intriguing emergent behavior. Toxic strains of Microcoleus co-exist with its non-toxic counterparts and other cyanobacteria. Many metabolic pathways of toxic Microcoleus species operate differently from conventional pathways of other cyanobacteria. Through a combination of laboratory and field scale testing using a suite of genomic and modeling tools, this project seeks to understand the spatial and temporal dynamics of Microcoleus and the rule of life controlling the dynamics and emergent behavior of Microcoleus genera leading to toxic benthic mats. The results are expected to open new opportunities in the ecological science of benthic toxic mats in freshwater streams and to be applicable to cyanobacterial bloom mitigation. This project will broaden participation and promote student training in environmental biology, data science, ecological engineering, chemistry, mathematical modeling and computer science with an emphasis on training students from underrepresented groups. Despite recent findings that toxic and non-toxic strains of Microcoleus synergize their metabolic efforts to facilitate each other during colonization, how nutrient concentrations, riverbed type, and other environmental factors play a role in the Emergent Rule of Life governing the colonization and toxin production in Microcoleus are not well understood. Therefore, the rule of life this project aims to investigate is how mat formation and toxin production by Microcoleus emerge from its interactions with its non-toxic counterparts and other coexisting bacteria in the benthic mats. The project will study (1) how within-mat species interactions and biogeochemical conditions facilitate Microcoleus growth and toxin production in low-nutrient streams, (2) the molecular mechanisms (e.g., gene expression level) by which toxic non-heterocytous (e.g., Microcoleus) and heterocytous cyanobacteria (diazotrophs able to fix atmospheric nitrogen gas, e.g., Anabaena) flourish in nitrogen and/or phosphorus deficient flowing waters and, (3) develop models to predict the occurrence and dynamics of toxic Microcoleus at river scales and quantify how cyanobacterial community dynamics and abiotic environmental conditions drive benthic cyanobacteria and toxin production over the growing season.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.