Date of Award

Spring 5-17-2014

Degree Type


Degree Name

MS Biology




Tin-Chun Chu, Ph.D

Committee Member

Angela Klaus, Ph.D

Committee Member

Sylvia Rabacchi, Ph.D

Committee Member

Allan D. Blake, Ph.D.

Committee Member

Jane L Ko, Ph.D.


Pseudomonas, antibacterial, natural products, polyphenolic compounds, biofilm


Pseudomonas is a genus of gram-negative gammaproteobacteria with a large range of diversity. Because of its ability to grow at low temperature, Pseudomonas is a cause of food spoilage. This bacterium is also a very common nosocomial infection of hospital patients. In this study, we investigated the effects of different natural products on Pseudomonas. The products included a polysaccharide, two flavonoids tangeretin and nobiletin and their derivatives, 5’OH-tangeretin and 5’OH-nobiletin, black tea polyphenol – theaflavins (TFs), as well as an herb named Fallopia multiflora (Chinese Knotweed). P. fluorescens and P. aeruginosa were used as model organisms. Antimicrobial effects were evaluated at various concentrations by using a microtiter plate assay or culture tube assay. The inhibition of biofilm formation was also determined using crystal violet assay. The results indicated that the selected natural products have antibacterial effect and anti-biofilm formation on Pseudomonas. Of the seven compounds studied 2.5% theaflavin, 2.5% Chinese Knotweed, and 500 μM of tangeretin showed the greatest antimicrobial effect.