Genetic and environmental factors driving E. coli attachment to particles in streams

有害微生物是30万英里长的河流和海岸线以及500万英亩湖泊受损的主要原因，这些河流和海岸线不符合美国的水质标准。由于缺乏对驱动微生物附着到颗粒上的机制的了解，对表面流中的微生物传输进行建模需要大量的假设。对颗粒的附着可能受到细菌表达促进附着的外膜特征的遗传倾向的影响，受有机颗粒或沉积物的物理化学特性、水化学或环境条件或这些因素的某种组合的影响。该项目的目的是提高我们对影响大肠杆菌附着在有机颗粒和水系沉积物上的遗传和环境因素的了解。该项目的目标是(1)评估环境相关条件下大肠杆菌对模拟河流颗粒的附着，并确定表面蛋白质和EPS对这种附着的相对贡献；(2)确定外膜蛋白和EPS对附着的影响，并确定能够表达这些特征的基因；(3)比较大肠杆菌的附着和脱离行为与表现出的附着倾向；以及(4)通过与模型颗粒的比较，评估大肠杆菌对实际河流颗粒物的附着的机制。我们将确定介导大肠杆菌与环境颗粒附着的遗传编码因素。所有的发现都将通过基因缺失实验来证实，以验证所提出的依恋中介基因在与环境相关的条件下对依恋的作用。实验将确定使大肠杆菌附着的颗粒特征，以及鼓励大肠杆菌从环境颗粒中分离的环境变化。需要获得关于大肠杆菌和颗粒之间相互作用的知识，以改善对微生物环境命运和运输过程的理解和建模，这对于保护高质量的水供应和确定可能存在公共健康风险的条件是重要的。了解病原体是如何通过溪流流动的，对于预测公共健康何时可能受到威胁很重要。病原体在水中移动时会附着在颗粒上，但尚不清楚这是由于细菌的遗传、颗粒的特性还是微生物周围的环境。该项目将探索影响淡水溪流中病原体和颗粒之间相互作用的许多因素。这一新知识将改进经常用于流域规模水质评估的微生物去向和运输模型。我们还将为贫困少数民族中学生开发基于发现的学习模块，并为几名研究生和本科生提供教育机会。

1236510SoupirHarmful microorganisms are the leading cause of impairments in the 300,000 miles of rivers and shorelines and 5 million acres of lakes that do not meet U.S. water quality standards. Modeling microbial transport in surface streams requires numerous assumptions because of the lack of understanding about the mechanisms driving microbial attachment to particles. Attachment to particles may be influenced by a genetic predisposition of bacteria to express outer membrane features that facilitate attachment, by physiochemical characteristics of organic particles or sediments, by water chemistry or environmental conditions, or some combination of these factors. The goal of the project is to improve our understanding of the genetic and environmental factors influencing E. coli attachment to organic particles and stream sediments. The objectives of the project are to (1) evaluate the attachment of E. coli to model stream particles under environmentally relevant conditions and determine the relative contribution of surface proteins and EPS to this attachment; (2) determine the effect of outer membrane proteins and EPS on attachment and identify the genes enabling expression of these features; (3) compare attachment and detachment behavior of E. coli with a demonstrated propensity for attachment; and (4) assess the mechanisms of E. coli attachment to actual stream particulates by comparison with attachment to model particulates. We will identify genetically encoded factors that mediate E. coli attachment to environmental particles. All findings will be confirmed by gene deletion experiments to verify the role of proposed attachment-mediating genes on attachment under environmentally relevant conditions. Experiments will identify particle characteristics enabling E. coli attachment and environmental changes encouraging detachment of E. coli from environmental particles. The knowledge gained about the interactions between E. coli and particles is needed to improve understanding and modeling of microbial environmental fate and transport processes, which are important for the protection of high quality water supplies and identifying conditions when a risk to public health may be present. Understanding how pathogens flow through streams is important for predicting when public health might be at risk. Pathogens attach to particles when they move through waters, but it is unknown if this is because of the genetics of the bacteria, properties of the particle, or the environment surrounding the microorganism. This project will explore the many factors influencing the interactions between pathogens and particles in freshwater streams. This new knowledge will improve models of microorganism fate and transport, which are frequently used in watershed-scale, water quality assessments. We will also develop discovery-based learning modules for underserved minority middle school students and provide educational opportunities for several graduate and undergraduate students.