Figure 7
Comparison of sensor output in the presence (solid circles) and absence (solid squares) of the positive feedback amplifier. Schematic of positive feedback design is shown in Figure 6. The design lacking positive feedback is otherwise identical to one with positive feedback except that only GFP is expressed from the P luxI promoter. In these experiments, cells were grown overnight at the indicated concentrations of aspartate prior to measurements. The fluorescence values were normalized with the OD600 absorbance to account for cell density. Inset figure shows the magnification of the response for the design lacking positive feedback. Error bars denote 95% confidence intervals for measured averages.