Quorum sensing is the term used to describe signaling pathways used by bacteria for intra and interspecies communication. Autoinducer 2 (AI2) is one signal molecule known to be involved in quorum sensing that stands out because it appears to be expressed across a wide variety of bacterial species. A genetic switch has been created exploits the AI2 quorum sensing pathway by turning on a target marker gene, green fluorescent protein, in the presence of AI2. The purpose of this investigation was to characterize this genetic switch and to investigate its behavior in mixed culture. Specifically to see if E. coli can respond to AI2 from other E. coli cells. It was found that the switch could be turned on by synthetic AI2 and AI2 being made by other cells growing in mixed culture as well by autoexpression.