Date of Defense


Date of Graduation



Biological Sciences

First Advisor

Jacqueline Eng

Second Advisor

Silvia Rossbach

Third Advisor

Charles Ide


Recent studies suggest that there are 1.3 times as many microbial cells as human cells in the body (Abbot, 2016). Another study claims that the combined genomes of this microbiota is 150 times that of the human genome (Zhuang & Shen, 2018). If you have ever had the feeling that you are not alone in an empty room you are most certainly correct. Your body is teeming with millions of organisms living in mutualistic symbiosis with you and surrounding microbes, but at times, this seemingly harmonious relationship can be disturbed, resulting in serious physical and psychological changes to the human body.

This thesis will explore many of the proven and possible ramifications of the oral and gut microbiota’s metabolic systems. Primarily, literature regarding the current understanding of the human microbiome will be explored. This includes studies that review common human microbiome compositions and various contributors to differing microbiomes such as geographical location and diet. Next, there will be a review of specific methods utilized by microbes to influence the human body. Benefits of homeostasis of the human microbiome will be described. Contrastingly, there is abundant literature that supports the notion that disorders of the GI tract and neurodegenerative disorders of the brain actually stem from microbiome dysbiosis defined as any deviation from homeostatic concentrations of bacteria. The possible use of probiotics, prebiotics, and fecal transplants will be considered as treatment for microbiome dysbiosis and related disorders. Finally, I will turn to a review of neurodegenerative disorders, with a focus on Alzheimer’s (AD) and its biological processes. Then I will expand on the dysbiotic microbial influence on the pathogenesis of AD. The conclusion of this paper will consist of possible holistic preventative measures for microbial dysbiosis and AD.

Access Setting

Honors Thesis-Open Access