Engineering and mathematical modelling of a microbial swimmer based biosensor

Summary form only given. Our goal here was to develop an Escherichia coli based sensing and actuation system. Here we divided the genetic circuitry required for actuation and sensing into two strains of E. coli and linked the two strains via a cell-cell communication signal. We targeted a quorum-sensing (QS) signaling molecule to control the motility response of our actuator strain. We demonstrated that the actuator cells showed signaling molecule dependent motility. Further, we developed a mathematical model that describes our engineered actuator system to provide insight into the key parameters controlling behavior of the system. As a model sensing system, we built an isopropyl β-D-1-thiogalactopyranoside (IPTG) sensor in E. coli. The sensor was designed to produce the QS signaling molecule in response to IPTG. We then demonstrated that the actuator cells respond to signaling molecule produced by this sensor strain. The sensing and actuation system engineered here can be used to build synthetic networks where motility is tightly regulated and controlled by cell-cell communication.