Current biosensors are limited in the sense that they produce digital outputs (either 0 or 1 output) in the presence of an inducer. In order to create a more useful biosensor, analog devices with wider ranges of outputs are necessary. In contrast to digital sensors, an analog device can measure an inducer across a spectrum; for example, an analog device could be used to pinpoint the concentration of iron in groundwater, whereas digital devices could only register whether the concentration exceeded a pre-defined threshold amount.
Our device, the bacterial tape recorder, will generate such analog outputs by converting chemical inputs into DNA based memory. Using the SCRIBE (Synthetic Cellular Recorders Integrating Biological Events) system developed by Timothy Lu’s lab at MIT, we aim to standardize a device that can characterize the intensity of and duration of events and store them for later retrieval. The SCRIBE system works by integrating plasmid DNA, later becoming specifically ssDNA into genomic DNA upon stimulation. By population analysis of cells that express the analog marker, we will use this system to monitor hazardous environmental factors such as heavy metals, which are known to be detrimental to groundwater in urban areas and developing countries.
We aim to introduce a degree of modularity that will allow future synthetic biologists to choose what inputs are the stimulus for analog recording.