Mass Spectrometry Guided Discovery of Microbial Specialized Metabolites

The overall themes of this dissertation revolve around the idea that recent advancements in mass spectrometry instrumentation and data analysis have had, and will continue to have, a major impact on biological research. Specifically, I demonstrate how the development of new analytical methodologies allowed me to pose new hypotheses as to the possible function and identity of microbial specialized metabolites. Chapter 1 provides an introduction to microbial metabolic exchange, mass spectrometry and an overview of the eventual analytical strategy employed to discover bioactive compounds in microbes: imaging mass spectrometry (IMS), tandem mass spectrometry (MS/MS) and mass spectral molecular networking. In Chapter 2, I describe my work in developing new strategies for imaging microbial systems using mass spectrometry. While similar in appearance, each of these methods allows the researcher to view a biological system from different molecular perspectives. When taken together, they provide insight more comprehensive than any single method is capable of. In Chapter 3, I describe my development of in vivo metabolic profiling using nanoDESI mass spectrometry as well as my role in the development of mass spectral molecular networking, a tool to organize and analyze MS/MS data. As tools for analysis of tandem mass spectrometry data are desperately needed in the field of life sciences, the popularity of mass spectral molecular networking (now known as Global Natural Products Social Molecular Networking or GNPS) has increased dramatically with our public web server handling around 400 runs per month. In Chapter 4, I give several examples of how I have used this recently developed 3-step workflow to answer biological questions across multiple systems. And finally, Chapter 5 describes ongoing and future work regarding using these techniques to find anti-malarial compounds produced from the gut microbiome of Plasmodium falciparum growth-inhibiting mosquitoes