Project Director

Giles, David K.

Department Examiner

O'Dea, Gregory; Barbosa, Jose; Santiago, Manuel


Dept. of Chemistry


University of Tennessee at Chattanooga

Place of Publication

Chattanooga (Tenn.)


AIM: This research had two primary objectives. First, this study sought to determine whether or not exposing Vibrio cholerae and Vibrio parahaemolyticus to polyunsaturated fatty acids (PUFAs) would lead to changes in their respective phospholipid profiles. Secondly, if membrane remodeling occurred, this study sought to determine the impact of membrane modifications on bacterial fitness by evaluating their effect on membrane permeability, biofilm formation, and response to stresses. METHODS: The Bligh and Dyer method was used to extract bacterial lipids, which were subsequently analyzed via thin-layer chromatography (TLC). The effect of fatty acids on bacterial fitness was assessed using stress, biofilm, and crystal violet (CV) assays. Stresses used include: lactic acid, hydrogen peroxide, and the antimicrobial peptide polymyxin B (PMB). RESULTS: TLC of isolated phospholipids from V. cholerae and V. parahaemolyticus grown in the presence of PUFAs indicated structural changes, suggesting incorporation of exogenous fatty acids into membrane lipids. CV uptake tests revealed fatty acid-dependent changes in permeability of up to 30% in V. cholerae and 20% in V. parahaemolyticus. V. parahaemolyticus displayed increased sensitivity to oxidative stress for all PUFAs, while exposure to docosahexaenoic acid (22:6) enhanced its resilience. The susceptibility of both V. cholerae and V. parahaemolyticus to PMB was increased. Following exposure to multiple PUFAs, biofilm assays revealed a reduced capacity for biofilm formation in V. cholerae for all fatty acids except 22:6. Furthermore, V. parahaemolyticus exhibited an increase of over 30% in biofilm activity. Significant exceptions to this behavior were 22:6 and 18:3γ which decreased biofilm production in V. parahaemolyticus by 30% and 70%, respectively. These results implicate fatty acids as important resources for bacterial membrane remodeling that may affect environmental persistence and host virulence in Vibrio species.


Special thanks to Dr. David Giles for allowing me to work in his laboratory. I had a great time working on this project and truly enjoyed myself. Additional thanks to Dr. Giles for mentoring me over the past few years. He has been an invaluable resource. Another special thanks to Dr. Manuel Santiago, Dr. Jose Barbosa, and Dr. Greg O' Dea, my DHON Committee, for their support and helpful, constructive criticism. Thank you all for helping me prepare to present at regional conferences in the Southeast. Thank you to Dr. Thao Gibson, Dr. Catherine Middleton, and Dr. Fred Gibson for critiquing my presentation and helping me prepare for my defense. Finally, thank you to UTC for my Provost Student Research Award and Grote monies use to fund this research.


B. S.; An honors thesis submitted to the faculty of the University of Tennessee at Chattanooga in partial fulfillment of the requirements of the degree of Bachelor of Science.




Cholera -- Haiti; Bacterial diseases -- Epidemiology


Vibrio cholerae; Vibrio parahaemolyticus; Stress resistance; Membrane remodeling; Homeoviscous adaptations



Document Type



60 leaves







Date Available


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Chemistry Commons