The causality dilemma between dysbiosis and cancer has given rise to numerous studies both exploring the mechanisms behind cancer progression and the associative shifts in the microbiota upon carcinogenesis. Aside from the hallmark study of Dr. Barry Marshall in establishing the true causal relationship between Helicobacter pylori and gastric adenocarcinoma, studies have only been successful in adding associative links of carcinogenesis mediated by bacteria to the literature. The current field is limited in its ability to establish causative relationships, and further work is needed to construct a reference community whose physiological responses reflect global community responses. In this thesis, the organism Lactobacillus acidophilus was selected as a pilot strain for the development of a novel framework to establish the fitness and physiological changes that occur when bacteria engage the human epithelial environment. The pilot strain was revived from the American Type Culture Collection (ATCC), verified through 16S rRNA Sanger sequencing, and grown in its conventional culture medium and human tissue culture medium to establish baseline growth rates and gauge its physiological responses to an in vitro tumor microenvironment. A set of standard conditions was proposed for growth under human tissue culture conditions. Finally, a metabolic study and spot plate assay were performed to elucidate the anabolic deficits and viability of this strain in human tissue culture medium, respectively. This research was performed to better understand the environmental and metabolic requirements for this pilot strain to inhabit the human epithelial environment, and to establish a workflow that will set the foundation for an appropriate clinical study to demonstrate the causative relationship between dysbiosis and carcinogenesis.
Bachelor of Science (B.S.)
College of Medicine
Burnett School of Biomedical Sciences
Mikhail, Samuel A., "Evaluating Lactobacillus Acidophilus as a Model Organism for Co-Culture Cancer Studies" (2019). Honors Undergraduate Theses. 587.