The emerging field of optogenetics has driven development of truly fascinating bacterial systems. Scientists have been able to achieve optogenetic control of cell function using engineered photoreceptors, edge detection of an illuminated design, and even patterns on cells with fluorescent proteins. The field still harbors a lot of potential that has yet to be explored. (S Karig)

The Penn 2015 iGEM team attempted to exploit this potential by using light to drive cell communication. Talk between bacterial populations, known as quorum sensing is reliant on diffusion of chemical autoinducers produced by the cell. This process enables microorganisms to modify gene expression as a function of cell density. The reliance of quorum sensing on chemical diffusion restricts communication to within common environments and compatible conditions. However, the use of bioluminescent sender cells and light-sensitive receiver cells to drive talk between cells overcomes these limitations. The system is effective across boundaries, in different environments, and in populations with different growth conditions or antibiotic resistances. Additionally, future research teams can also take advantage of the orthogonality of light to chemicals and spatiotemporal control of light in any future project endeavors.

The design of our project was inspired by an electrical engineering system known as a photocoupler (pictured below.)

This component works by transferring electrical signals between isolated circuits by using light. Our system is a biological analog of the optocoupler, a cell-to-cell communication system in which a "sender" cell transfers a light signal to an isolated "receiver" cell, which expresses photoreceptors to enable a light-dependent response. (CITATION) Please click on the links below to learn more about the individual components of our project.