The role of heterotrophic bacteria in protecting cyanobacteria from hydrogen peroxide in coastal systems.

有毒蓝藻有害藻华（CHAB）现在是一个世界性的问题，对人类和水生生物构成危险，包括危及生命的疾病，海滩关闭，健康警报，饮用水处理厂关闭。 该项目的重点是了解CHAB中存在的微生物与它们所居住的湖泊化学之间的相互作用所需的基础科学。 特别是，它将研究过氧化氢的来源，命运和影响，这是对这些水华中存在的毒性和物种的潜在重要控制。 这项研究将在伊利湖进行，该湖是每年受到CHAB威胁的1100万人的饮用水源。 结果将直接纳入水管理人员和其他利益攸关方广泛使用的两个水质模型。 该项目将支持培训两名博士生，包括第一代大学生，以及来自地球科学背景的本科生。 研究也将被纳入旨在增加地球科学的多样性，涉及妇女和代表性不足的少数民族在K-12，以及大学和成人教育settings.The总体目标是确定过氧化氢（H2 O2）对蓝藻群落的组成和功能在近岸生态系统的影响。 从湖伊利的初步结果表明，占主导地位的初级生产者依靠异养细菌提请H2 O2从短暂的高环境水平，可能抑制蓝藻群落的成员。 这表明H2 O2在水生微生物生态学中起着重要的作用，但人们对其了解甚少。 结合现场采样，实验，和国家的最先进的“组学”将被用来测试的整体假设，H2 O2分解异养“帮手”是一个重要的决定因素，微生物的相互作用和社区结构和功能。 伊利湖将进行研究，因为（一）它是一个模型系统，为浅水沿海地区接收高陆地养分径流，（二）它提供了强大的近岸-离岸梯度的光和养分的比较研究，和（三）现有的采样基础设施，存档的样本，和初步数据可以利用。 现场和实验室的实验和测量将被整合，以回答以下问题：Q1：是什么驱动H2 O2浓度的时间动态？ Q2：哪些酶和生物体负责通过生物H2 O2衰变保护社区？ 问题3：帮助者对H2 O2的保护如何影响社区的组成和功能？ 该研究将在水华的不同时间点对培养物和天然沃茨进行受控实验室实验。 将采用H2 O2浓度、产生率和衰变率的测量方法，沿着辅助化学和生物测量方法，评估H2 O2的主要来源和汇。 分子工具将被用来确定的途径支撑H2 O2衰减和H2 O2对蓝藻群落组成功能的影响。 与此同时，不同的H2 O2浓度对主要蓝藻的生长速率的影响将进行实验评估。 这些实验结果将被放置到背景下，通过比较的结构和功能的微生物群落从现场样品跨越空间，时间和化学梯度在这个沿海生态系统。 将H2 O2与自然系统中的“组学”相结合的研究方法是新颖的，将促进我们对微生物群落组成和功能之间关系的基础知识和理解。

Toxic cyanobacterial harmful algal blooms (CHABs) are now a worldwide problem that poses dangers for humans and aquatic organisms including life-threatening sickness, beach closures, health alerts, and drinking water treatment plant closures. This project focuses on the basic science needed to understand interactions between the microorganisms present in CHABs and the chemistry of the lakes they inhabit. In particular, it will study the sources, fate, and effects of hydrogen peroxide, which is a potentially important control on the toxicity and species present within these blooms. This research will be conducted in Lake Erie, a source of drinking water for 11 million people that is threatened by CHABs annually. Results will be directly integrated into two water quality models that are widely used by water managers and other stakeholders. This project will support the training of two PhD students, including a first-generation college attendee, and undergraduate students from backgrounds that are underrepresented in the earth sciences. Research will also be integrated into outreach aimed at increasing diversity in the earth sciences by involving women and underrepresented minorities in K-12 as well as college and adult educational settings.The overall goal of this project is to determine the influence of hydrogen peroxide (H2O2) on cyanobacterial community composition and function in nearshore ecosystems. Preliminary results from Lake Erie show that dominant primary producers rely on heterotrophic bacteria to draw down H2O2 from transiently high environmental levels that are likely inhibitory to members of the cyanobacterial community. This suggests that H2O2 plays important and still poorly understood roles in aquatic microbial ecology. A combination of field sampling, experiments, and state-of-the art "-omics" will be used to test the overall hypothesis that H2O2 decomposition by heterotrophic "helpers" is an important determinant of microbial interactions and community structure and function. Lake Erie will be studied because (i) it is a model system for shallow coastal areas receiving high terrestrial nutrient runoff, (ii) it offers strong inshore-offshore gradients of light and nutrients for comparative studies, and (iii) existing sampling infrastructure, archived samples, and preliminary data can be leveraged. Field and laboratory experiments and measurements will be integrated to answer the following questions: Q1: What drives the temporal dynamics of H2O2 concentrations? Q2: Which enzymes and organisms are responsible for protecting the community via biological H2O2 decay? Q3: How does protection from H2O2 by helpers influence the composition and function of the community? The study will perform controlled lab experiments on cultures and on natural waters during different points of the bloom. Measures of H2O2 concentrations and rates of production and decay, along with supporting chemical and biological measurements, will be used to assess the major sources and sinks of H2O2. Molecular tools will be used to determine the pathways underpinning H2O2 decay and the effect of H2O2 on cyanobacterial community composition function. In parallel, impacts of varying H2O2 concentrations on growth rates of major cyanobacteria will be assessed experimentally. These experimental results will be placed into context through comparisons with the structure and function of microbial communities from field samples across spatial, temporal, and chemical gradients in this coastal ecosystem. The approach of integrating studies of H2O2 with "-omics" in natural systems is novel, and will advance our fundamental knowledge and understanding of the relationship between microbial community composition and function.