Davidson College Department of Biology Honors Thesis Title: Constructing and Implementing a Transcription-Based XOR Gate in Escherichia coli through Promoter Engineering

Synthetic biology is an emerging scientific field that utilizes biological principles to predictably engineer organisms to perform useful functions. In addition to holding great potential for solving real world problems, this multidisciplinary field offers valuable insight into specific areas where our understanding of biology is incomplete or wrong. Before complex systems can be engineered, it is important that simpler, wellcharacterized devices be developed. Towards that end, I have begun the construction of a modular XOR gate in E. coli that takes advantage of quorum-sensing transcription factors and promoter binding sites from Pseudomonas aeruginosa and Vibrio fischeri. This synthetic device was designed to perform XOR logic using two auto-inducer inputs to determine the transcriptional level of an interchangeable output gene. In addition to constructing this synthetic device, I also characterized a newly developed method for growing E. coli colonies in a time-delayed manner. Once the construction of the XOR gate promoters is completed, it will be possible to combine them with the time-delayed growth system to attempt to engineer a hash function in bacteria.