Our team was inspired by a 2013 paper by Hwang et al. titled “Reprogramming Microbes to be Pathogen-Seeking Killers”. Hwang et al. engineered E. coli to detect and fight Pseudomonas aeruginosa infections using a seek-and-kill technique. Their design is modular, which makes it possible to use their approach to target different bacteria. We found that the rise of antibiotic resistant bacteria makes it increasingly vital to find new treatments, which inspired us to adapt the system devised by Hwang et al. to target antibiotic resistant bacteria. We identified Methicillin-Resistant Staphylococcus aureus (MRSA) as our target and did extensive research to adapt the Hwang et al. system to target MRSA. When reviewing past iGEM projects, we found that TU Delft completed a similar project in 2013. TU Delft used the agr quorum sensing system from Staphylococcus aureus to detect AIP produced by MRSA. This sensing system was then coupled with antimicrobial peptides produced by toads and frogs to kill MRSA. We intend to adapt and improve this system by first optimizing the agr sequences and adding the SarA gene, which we hypothesize will improve the function of the agr system. Secondly, we will use the CheZ gene to influence chemotaxis and cause E. coli to move towards MRSA after AIP is detected. Lastly, we will use garvicin KS, an antimicrobial peptide produced by Lactococcus garvieae, to destroy MRSA cells. We plan to first test each component in the system using a pBAD promoter to verify functionality. Pending success, the pBAD promoters controlling the motility and killing modules of the system will be replaced with P2 promoters. This will allow the agr system to activate motility and garvicin KS production after detection of AIP, creating a complete unit.
