Figure 3.

The performance of biosensors toward different metal ions. TOP10/pPcad-vio during the early exponential phase was exposed to four kinds of metal ions. After being cultured at 37 °C for 1.5 h, the bacterial densities (a) and the violacein signals (b) were measured at 600 nm and 578 nm, respectively. The red dotted box shows the pigment signals derived from the biosensor without exposure to metal ions. (c) A representative photo of butanol extraction phases from four independent experiments with similar results is shown here.