UC San Diego

As I am preparing my dissertation, a global Coronavirus pandemic is spreading, affecting the way we travel, work, and communicate. Transmitted primarily via respiratory droplets, this virus spread across the entire globe in a matter of months, highlighting the interconnectedness of modern life and the microscopic world which invisibly underlies all our interactions.

In fact the vast majority of life on earth is microbial, and for the vast majority of time microorganisms were the only life present. Animals emerged in a robust microbial world, and our evolution was shaped by and from these microorganisms.

Even during this global pandemic, it is easy to view ourselves as distinct, independent organisms. But recent evidence challenges this notion. Roughly 1% of our body weight is comprised of trillions of microorganisms, collectively referred to as the human microbiome. Our microbiomes are necessary for healthy nutrition, immune function, and even reproduction. How our microbiomes are formed, maintained, shared, and perturbed are active areas of research. My doctoral research focused on understanding and improving the molecular tools used to evaluate microbial communities and applying those tools to better understand human microbiomes.

This dissertation begins with three reviews summarizing what we know about human microbiomes and what is still lacking. Chapters 2 and 3 describe benchtop and computational advances to the human microbiome field, respectively. The final chapter includes two research articles currently under review describing the application of these tools to gain novel insight about human oral microorganisms.

Throughout my research, I found that human saliva served as a valuable tool for developing these novel techniques because it is simple to collect, high biomass, and relatively easy to manipulate. So although it was not my original intention, I have come to appreciate saliva as a valuable resource for pushing the boundary of human microbiome research. It is my hope that this research improves our ability to evaluate microbial communities, allowing for future research on altering microbiomes to improve human and environmental health.