Exploring the impact of peracetic acid on bacterial regrowth and plasmid release and developing a novel whole-cell biosensor to monitor the expression of quorum sensing genes
Abstract
[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Peracetic acid (PAA or CH3COOOH) is a promising alternative to chlorine-based disinfectants for water and wastewater treatment due to its strong antimicrobial properties and low disinfection by-product (DBP) formation potential. Numerous studies have determined the disinfection performance of PAA; however, issues such as the thermodynamic properties of PAA, bacterial regrowth after PAA disinfection, and the impact of PAA treatment on the release of bacterial plasmid DNA from water and wastewater treatment facilities are still poorly understood. In addition, it is important to understand how environmental stress or chemical disinfection affects bacterial gene expression, especially those involved in biofilm formation. Pseudomonas aeruginosa is a model bacterium for studies of microbial biofilm formation and pathogenesis, and both processes are tightly regulated by quorum sensing (QS) networks. Fluorescence-based whole-cell biosensing is a powerful tool capable of assessing the expression of bacterial genes, but an approach to simultaneously determine the genetic activities of the QS systems in P. aeruginosa has not been fully explored. This study aimed to determine the physicochemical and biological behavior of aquatic environments exposed to PAA as well as construct a novel whole-cell biosensor to assess the expression of important QS genes. Specifically, we focused on 1) calculating the important thermodynamic characteristics, Gibbs energy of formation and oxidationreduction (redox) potential, of PAA; 2) monitoring the long-term regrowth of both planktonic (suspended) and biofilm bacteria after PAA disinfection; 3) determining the impact of PAA treatment on the release and functionality of bacterial plasmid DNA; and 4) constructing a novel whole-cell biosensor to monitor the genetic activities of the four QS networks in P. aeruginosa PAO1 simultaneously, namely the las, rhl, pqs, and iqs systems.
Degree
Ph. D.
Thesis Department
Rights
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