Date of Award


Degree Type


Degree Name

MS Microbiology




Tinchun Chu, Ph.D.

Committee Member

Jane L. Ko, Ph.D.

Committee Member

Daniel B. Nichols, Ph.D.


Bacillus, spores, germination, natural product, green tea, EGCG


The Gram-positive Bacillus species is known for their spore-forming abilities. These spores are highly resistant to a multitude of factors such as heat, UV radiation, and chemical solvents, which can be attributed to the location of its DNA, and other components that make up the spore as a whole. Bacillus spp. can be detrimental to the food & beverage industry and the medical field due to their production of enterotoxins, which can manifest as bacterial infections. Antibiotic-resistant bacteria towards current treatments are of major concern, and thus the need for alternative therapeutic agents is urgent. The beneficial health properties of the green tea drink can be attributed to the green tea polyphenol (GTP) epigallocatechin-3-gallate (EGCG) and several other GTPs found within the leaves of Camellia sinesis plant. In this study, the potential effects of a modified lipid-soluble GTP, epigallocatechin-3-gallate-palmitate (EGCG-P) was evaluated due to its structural stability when compared to EGCG alone. Antibacterial activities of EGCG-P-based formulations on Bacillus cereus, Bacillus megaterium, and Bacillus subtilis were examined. A microplate assay was carried out to determine the minimum inhibitory concentration (MIC) and half maximal inhibitory concentration (IC50). A colony forming unit (CFU) assay was used to evaluate the percent of inhibition of the Bacillus spp. Flow cytometry was used to further investigate the susceptibility of the bacteria to the formulations. Germination assay and SEM imaging was used to evaluate the effectiveness of the formulas on the germination and on the spores itself. Lastly, bioinformatics software QIAGEN Ingenuity Pathway Analysis (IPA) was explored to propose an anti-germination mechanism of EGCG on the Bacillus spp. The results from this study indicated that EGCG-P based formulations possess strong antibacterial effects against all three Gram-positive bacteria as well as potential anti-spore properties, making it a viable alternative as a natural therapeutic agent.

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