Project Director

Giles, David K.

Department Examiner

Ferdoush, Jannatul; Spratt, Henry


Dept. of Biological and Environmental Sciences


University of Tennessee at Chattanooga

Place of Publication

Chattanooga (Tenn.)


Antimicrobial peptides (AMPs) are found in all organisms and have gained attention for their effectiveness against a variety of pathogens. Piscidins are AMPs that were discovered in mast cells of vertebrates, mostly within marine animals, and are an important part of the innate immune system due to their potent antimicrobial properties. Piscidin 1 (P1) and piscidin 3 (P3) are found within sea bass and have different antimicrobial activities. P1 exhibits strong membrane disruptive properties, while P3 goes through the membrane to the targeted DNA. These piscidins can experience metalation with copper (Cu2+) which enhances their antimicrobial activity in vitro (P1-Cu2+ and P3-Cu2+). V. parahaemolyticus is one of the leading foodborne pathogens in humans, causing acute gastrointestinal and immunological disorders. V. vulnificus has high mortality (18%) and economic burden ($320 million/year worldwide), causing necrotizing fasciitis and sepsis leading to approximately 100 deaths per year in the United States. The purpose of this study was to investigate the activity of metalated and nonmetallated P1 and P3 on Vibrio parahaemolyticus and Vibrio vulnificus, as the Vibrio genus possesses the ability to modify membrane permeability based on the available ambient fatty acids. To examine polyunsaturated fatty acid (PUFA) impacts on piscidin activity, we performed membrane permeability assays with the hydrophobic crystal violet and minimal inhibitory concentration (MIC) assays with linoleic (18:2), arachidonic (20:4) and docosahexaenoic (22:6) acids. In V. parahaemolyticus, PUFAS raised the MIC for P1 and P1-Cu2+ while the opposite effect was observed with P3 and P3-Cu2+. The data highlights antimicrobial susceptibility differences dependent upon the piscidin isoform. Each PUFA caused a distinct change in membrane permeability, while the effects of each piscidin were variable. In V. vulnificus, at least one PUFA raised the MIC of each piscidin. All PUFAs lowered permeability, but significant piscidin-dependent effects were observed with P1 only. The data herein sheds light on bacterial membrane dynamics regarding piscidin activity and PUFA-mediated effects which could potentially be used as future treatment for infectious diseases.


I would like to thank Dr. Giles for being my thesis director and allowing me to work in his lab. He has been an excellent mentor and taught me valuable Microbiology concepts. I would also like to thank Myram Cotton who provided the antimicrobial peptides, known as piscidins, used in this study. Lastly, I would like to thank Dr. Ferdoush and Dr. Spratt for taking time out and serve on my committee.


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.




Foodborne diseases; Gastrointestinal system--Diseases; Microbial sensitivity tests; Unsaturated fatty acids; Vibrio parahaemolyticus--Detection; Vibrio vulnificus


Antimicrobial peptides ; Piscidins; Polyunsaturated fatty acids; Vibrio parahaemolyticus; Vibrio vulnificus


Pathogenic Microbiology

Document Type



54 unnumbered leaves