The Role of Extracellular Polymeri Substances of Biofilm on Pathogen Disinfection in Water Distribution Systems

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0933288SeoImmobilized microbial cells grow and produce extracelluar polymeric substance (EPS), which create structured communities of microorganisms. Together, immobilized cells and EPS form a biofilm. Reports from many water utilities in the US have shown that biofilm survives in water distribution systems despite the continuing presence of disinfectants and causes significant health threats to the public. Currently, the persistence of biofilm in water distribution systems is believed to be strongly related to EPS. The principal objective of this proposal is to understand the mechanisms of the persistence of biofilm in water distribution systems. Emphasis will be placed on understanding the role of biofilm EPS, using microelectrodes techniques and fluorescently labeled probes for in-situ biofilm monitoring. The proposed studies with microelectrodes techniques and biofilm analysis tools will broaden our understanding of pathogenic biofilm formation and its control with disinfectants. Specifically, this research will enable quantitative evaluation of the role of EPS and biofilm structure on the transport and reaction of disinfectants. This will result in the development of modeling parameters obtained with microelectrodes and biofilm analysis. In addition, we will identify the role of EPS on pathogen attachment, detachment and redistribution. Finally, this research will result in combined assessments of the effects of multiple distribution parameters (water age, reactive pipe material, phosphorous corrosion inhibitor) on multi-species biofilm growth. This research has new key approaches which can be differentiated from previous studies. First, the unanswered transport and reaction kinetics of secondary disinfectants in biofilm will be determined with newly developed microelectrodes and in-situ biofilm analysis. Second, a systematic approach will be used to observe the role of EPS on the detachment and redistribution of biofilm, monitoring physiological states of detached clusters which couldn't be understood with particle size analyzers. Beyond enlarging our understanding of biofilm control in academic society, the proposed research has direct and broad impacts on water utilities, industries, and public health. The information gleaned from this research will enable local water utilities to incorporate biofilm control strategies and enhance our current understanding of biofilm control mechanism in many other industries including medical and chemical industries. The outcomes will contribute to protecting public health by improving the prevention of biofilm related pathogen infection via drinking water and providing a fundamental understanding of the role of EPS against antimicrobial agents. In addition, the proposed project will result in the training and education of two Ph.D students, summer research opportunities for undergraduate and high school students, and implementation of research findings into PIs three undergraduate courses.