Figure 4

Influence of the variability in individual growth rate and septum positioning on the cell size distribution. (A) Size distributions simulated using the Size Model with the division rate B_s estimated from f₁ data and an exponential growth (v(x)=v x). In blue: Simulations with the same growth rate v=0.0274 for every cell. Red dashed line: Simulations with individual growth rates distributed according to the experimentally observed distribution. Green line: Growth rates normally distributed with coefficient of variation CV =60%. Inset: Difference (i.e. normalized integrated squared error) between the size distribution simulated without variability and the distributions simulated with various levels of variability (normally distributed individual growth rates of CV between 10% and 60%). (B) Simulated size distributions using the Size Model with the same division rate B_s as in A and a constant growth rate v=0.0274. In blue: Simulations where division is perfectly symmetrical. Red dashed line: Simulations with a variable septum position distributed according to the experimentally observed distribution. Green line: Simulations with a normally distributed septum position with CV =30%. Inset: Difference between the size distribution simulated without variability in the septum position and the distributions simulated with various levels of variability (normally distributed septum position of CV between 5% and 30%). CV, coefficient of variation.