Date of Award

5-2017

Document Type

Thesis

Degree Name

Master of Science (MS)

College/School

College of Science and Mathematics

Department/Program

Biology

Thesis Sponsor/Dissertation Chair/Project Chair

Lee H. Lee

Committee Member

Sandra Adams

Committee Member

Ann Marie DiLorenzo

Abstract

Endospores are dormant structures of endospore-forming bacteria, such as Bacilli and Clostridia, which enable them to become resistant to any harsh environmental conditions such as heat, chemicals, and UV radiation, thus surviving for many years. When the environment is favored for growth, the spores undergo the germination process which enables them to become vegetative cells again. This becomes a threat to the food and medical industry as they can cause food spoilage, food poisoning, and contamination.

Green tea, made from the plant, Camellia sinensis, has become the second most consumed beverage in the world due to its medicinal benefits. It consists of polyphenols which have been found to have anti-inflammatory, antimicrobial, anti-cancerous, and antioxidant properties.

In this study, EGCG and EGCG-S were examined to determine their inhibitory effects on the endospores of Bacillus cereus (B. cereus), B. megaterium, and B. subtilis. Different concentrations of EGCG-S (100, 400, and 1000ug/mL) were tested on vegetative cells to determine if they were able to inhibit bacterial growth. Both EGCG-S 400 and 1000pg/mL concentrations inhibited 99-100% of bacterial growth, whereas EGCG-S 100 inhibited at least 88%. For sporulation, EGCG-S (100, 400, 1000, and 10,000ug/mL) inhibited 99-100% sporulation at 24 hours, and 1% EGCG inhibited 95- 100%, suggesting that EGCG-S does not act in a dose-dependent manner, and that it is a better agent against sporulation. For spore germination, EGCG-S (100, 400, 1000ug/mL) inhibited at least 95% of spore germination in B. cereus at 5 minutes, while at least 80% were prevented for B. megaterium and B. subtilis at 10 minutes. The Live and Dead Assay qualitatively confirmed these results The SEM also further supported that the EGCG-S was able to inhibit spore germination by destroying the cell wall of the spore. Lastly, EGCG-S and tea antiseptics Hsu (TAX) were used to determine their potential use as disinfectant or antiseptic on spore contamination using Rapid Agar Plate Assay (RAPA) and Time Course Study, respectively. EGCG-S (100, 400, 1000, and 10,000ug/mL) were able to prevent at least 80% of pre-treated and contaminated agar surfaces, while TAX inhibited at least 94% of spore germination in all three Bacillus spp. at 30 seconds, and increased to 97% at 1 minute. These show that EGCG-S and TAX may become potential anti-endospore agents in targeting Bacillus spp., thus aiding in the prevention of food and beverage spoilage caused by endospore-forming bacteria as well as contamination in the medical industry.

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