Figure 1

Scheme of the system and dynamical simulation at the single cell level. (a) Scheme of the synthetic gene cassette and the fully regulated promoter forming a delay-inducing DNA loop. Arrows (blunt lines) mean positive (negative) regulations. (b) Quorum sensing scheme. Each cell produces AHL which is pumped to the medium, allowing cell population to reach a homogeneous concentration of AHL. (c) Simulation of the circuit behavior at the single cell level showing oscillations with the nominal parameters (Table 1). The initial condition is given by no molecular species in the system and with no IPTG in the medium. (d) Normalized oscillatory frequency versus the amount of IPTG (vertical line gives the limit where the sustained oscillations are lost, i _c ≃ 0.085).