UC Riverside

Bacteria transport in aqueous environments is heavily influenced by nanoscale forces that govern deposition on and detachment from environmental surfaces. Surface interaction can prevent these species from being carried long distances by fluid flow. Nuances in deposition and detachment properties of waterborne pathogenic bacteria can xii mean the difference between life and death or serious economic losses. In this dissertation, deposition and detachment properties of the human pathogen Escherichia coli O157:H7 and the plant pathogen Xylella fastidiosa are analyzed using a variety of engineering tools. Sand column experiments, parallel plate experiments, and thermodynamic surface interaction predictions are used to study how nanoparticles could affect the transport of E. coli O157:H7 in agricultural soils. Results indicate that the presence of titanium dioxide (TiO2) nanoparticles in agricultural waters could increase E. coli O157:H7 soil transport, especially during rain events. However, the presence of copper oxide (CuO) nanoparticles may decrease E. coli O157:H7 transport. Xylella fastidiosa transport in an insect-plant system was studied in silico. Fluid flow fields in this system were simulated and integrated with custom-made MATLAB code to predict bacteria detachment under relevant environmental conditions. Results support a model of key fluid dynamic mechanisms involved in X. fastidiosa spread within plants and between plants. The model can be used to investigate potential targets for fighting costly crop diseases caused by X. fastidiosa. The application of computational and experimental tools in this dissertation demonstrate how engineering methods can enhance analyses of bacterial transport in diverse environmental systems.