Communication between cells is instrumental in coordinating population-level activity. In a process known as "quorum sensing," bacteria both secrete and sense autoinducer signaling molecules to enable synchronization of group gene expression paradigms. The synthetic biology community has rapidly adopted these quorum signaling pathways for use in programmed circuitry. However, chemical signals must diffuse between sender and receiver cells, limiting such communication to a common environment. In electronics, when electrical signals must be transferred between two circuits operating at incompatible voltages, electrical engineers use optocouplers, components that transfer information between isolated circuits via light. The 2015 Penn iGEM team presents a biological analog of the optocoupler, a cell-to-cell communication system in which a "sender" cell generates light via bioluminesence and a "receiver" cell expresses photoreceptors to enable light-dependent physiological responses. We show that light elicits a response in light-sensitive receivers and illuminated potential applications for this alternative form of cell communication.

Analagous to our project goals, the Penn iGEM 2015 team has worked to further illuminate the parallels between genetic circuits and electrical circuits with the addition of the PennTunes Toolbox. Just as there is a distinct change in response when replacing an electric circuit component, the various genetic parts included in this toolbox clearly demonstrate the divergence in expression level due to a change in genetic parts such as promoter strength, RBS, etc. As an example, we have characterized one of the inverter strains in the toolbox that exhibits the relationship in the figure to the right.

Our aim so to increase the reach of synethetic biology by providing the tools and infrastructure that will make biotechnology more accessible in educational settings and citizen science. Find out more about our vision of the future for synthetic biology and personal biotechnology tools by clicking on the graph!