UC San Diego

Programmed cell death is a common theme in biology. Apoptosis in eukaryotic cells is typically mediated by external signals and is important for development and tissue homeostasis. There is also a growing body of evidence showing that programmed cell death also occurs in bacteria, and is important for biofilm formation. With the growing amount of tools for the genetic engineering of bacteria, researchers have made genetic constructs where bacterial cell death could be controlled or induced to further our understanding of bacterial cell death and it's prospective use in applications. Concurrently, researchers in the field of synthetic biology have succeeded in developing dynamic gene circuits, such as oscillators and toggle switches, which operate at the intracellular (protein) level. In this dissertation, I discuss the engineering of bacteria via a gene circuit which can produce dynamic behaviors of the population by synchronizing bacterial cell lysis.

In Chapter Two, I discuss the construction and characterization of this circuit, which is called the Synchronized Lysis Circuit (SLC). The engineered bacteria are then used as a vehicle to deliver therapeutic proteins to tumors via synchronized lysis. In Chapter Three, I discuss the application of the SLC in stabilizing a competitive ecosystem of bacteria. In Chapter Four, I discuss the effects of lysis protein production at the single-cell level on growth and survival. In Chapter Five, I discuss the behavior of the SLC at different scales (micro to macro) and it's evolution over time. All of these sections combine to describe the behavior of synchronized lysis from single-cells to populations, and the applications of such a system.