Figure 6. Addition of Orthogonal Operon Yields Nuanced Predation Habits.

(A) The toggle switch topology modified with an additional, orthogonal operon containing the P_lux-λ promoter driving polycistronic expression of GFP and mCherry was simulated. This promoter is induced by AHL, which the robot is programmed to inject into the living, onboard microbiome when it nears any carbon depot. (B) Simulation results for internal inducer concentrations of lactose (cyan), arabinose (orange), and AHL (yellow). (C and D) Simulation results for internal fluorescent protein reporter concentrations of mCherry (red) and GFP (green) are shown in (D). These are parsed into the EFM electronic output shown in (C). Note the addition of EFM values of 2 and -2 indicating the robot is moving at two times the base velocity. (E) A simulation of resulting robot motion depicts the robot moving towards a depot, pausing, and then moving at twice the speed when close to the depot. This behavior appears to be qualitatively similar to stalk-pause-strike predation, an identifiable trait in higher level organisms.