Fig. 7.
Analysis of the biological variability within an isogenic bacterial population as determined with the flow cytometer and our microscope set-up. In a the dependence of the CV2 [computed as (σ/μ)2] on the concentration of IPTG is investigated through a dose response curve. The agreement between the data acquired with the alternative set-ups is very good, with only a slight tendency of the microscope setup (red dots) of underestimating the variable of interest, due to the higher dynamic range of the flow cytometer (blue dots). b The correlation graph supports these considerations, since the relation between the data acquired with the two instruments has a linear trend (green line R 2 > 0.99). Only the data point with the highest CV2, corresponding to the lowest induction level, deviates from linearity (as presented in Fig. 6b). Again a quadratic function fits better the relation between the two datasets at the rightmost end of the dynamic range, likely due to the higher sensitivity of the flow cytometer (cyan line, MSE = 1.8 x 10-4). The linear equation and the parabola that best fit the data points are reported below. CV2 Micro = 1.28 CV2 cyto -0.13. CV2 Micro = -0.61(CV2 cyto)2 + 1.58 CV2 cyto -0.13