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Genetic And Environmental Factors Driving E. Coli Attachment To Particles In Streams

Abstract

<p>Harmful 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.</p>

Investigators
Soupir, Michelle L
Institution
Iowa State University
Start date
2012
End date
2015
Project number
1236510