Date of Award

Spring 5-16-2015

Degree Type

Thesis

Degree Name

MS Microbiology

Department

Biology

Advisor

Tin-Chun Chu, Ph.D

Committee Member

Angela V. Klaus, Ph.D

Committee Member

Daniel B. Nichols, Ph.D

Committee Member

Allan D. Blake, Ph.D

Committee Member

Jane L. Ko, Ph.D

Keywords

antibacterial, chinese knotweed, polygonum multiflorum, bacteria

Abstract

Polygonum multiflorum, commonly known as Chinese Knotweed, is a tonic herb primarily used to enhance bodily functions. Recently, it has been shown to contain strong antioxidant, antibacterial and antiviral activity. The extract from the roots of Chinese Knotweed was used to assess its antibacterial properties against a broad spectrum of bacterial species, including 5 Gram-positive (B. cereus, B. megaterium, S. epidermidis, S. mutans and S. pyogenes) and 4 Gram-negative (E. aerogenes, E. coli, P. vulgaris and P. aeruginosa). Microtiter assays were carried out to evaluate the antibacterial activity of Chinese Knotweed at 0.5%, 1%, 1.5% and 2.5% concentrations in order to determine the Minimum Inhibitory Concentration (MIC). Potential synergistic effect of Chinese Knotweed and various antibiotics was assessed using the Kirby-Bauer disk method. Possible anti-biofilm formation was studied using a Congo-red assay, and biofilm quantification was acquired through crystal violet assay. Finally, Chinese Knotweed was evaluated on the effects of inhibiting sporulation and germination of B. megaterium. The results suggest Chinese Knotweed contains strong antibacterial effects against all the bacteria tested in this study and the MIC was 2.5% for all. Chinese Knotweed also showed significant synergism with most of the antibiotics tested. In addition, anti-biofilm assay indicated that 1% Chinese Knotweed was sufficient to inhibit biofilm formation on most the bacteria, while 2% Chinese Knotweed was effective for inhibiting sporulation and germination of B. megaterium spores. Thus, Chinese Knotweed may serve as a novel compound in the treatment and management of bacterial infections and biofilm formation.

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