Lag phase and recovery in rapidly fluctuating environments.

<p>A) When glucose and lactose alternate with environmental duration <i>T</i> = 30 minutes, uninduced cells () enter a lag phase following the first exposure to lactose only. No lag phase is measured at <i>t</i> = 60 minutes, indicating that cells are fully induced when lactose is reintroduced. B) Similarly, when the environmental duration is 10 minutes, cells only spend the first lactose exposure in a lag phase (N = 5 GCs, error bars = SEM). C) Amount of time uninduced cells were exposed to lactose conditions before reaching complete growth recovery. Under environmental durations <i>T</i> = 10 and 30 minutes, cells recover following 20 and 30 minutes of lactose exposure, respectively, compared with the 55 minutes necessary when the environmental duration . D) Cells pre-induced at have a 25 minutes lag+recovery phase (N = 5 GCs, error bars = SEM). Exposure to rapidly fluctuating glucose/lactose conditions increases adaptation rate, and cells are able to recover after only one exposure to lactose for environmental durations <i>T</i> = 5, 10 and 15 minutes. E) Measured lag+recovery times for pre-induced cells exposed to fluctuating conditions with an environmental duration <i>T</i> = 3-60 minutes. Error bars = standard error obtained from lag+recovery regression parameters. All datapoints from <i>T</i> = 3–15 minutes indicate that cells recover shortly after glucose is reintroduced (red line indicates cases where the lag+recovery times and <i>T</i> are equal), demonstrating that cells are able to fully grow on lactose after a single exposure to lactose conditions.