Figure 2.

(a) Representative output of two-color biosensors showing two extreme cases in which sensor output does not switch (left, right) and two intermediate cases demonstrating a shift in concentration of zinc at which sensor switches from lycopene-dominated to β-carotene-dominated (middle). (b) Carotenoid output comparing regulator pairs. While a substantial difference between regulator pairs was observed with fluorescent reporters (Figure 1c), two different pigment reporters (32L and 34L) show different lycopene production behavior in response to zinc but little difference in carotenoid production as a function of regulator pair. Error bars indicate standard deviation.