Survival Kinetics of Starving Bacteria Is Biphasic and Density-Dependent
Fig 3
Quantitative analyses of the survival kinetics of wild type cells.
(A) The log-log plot of log (N0/NCFU), where N0 is the number of CFU at the time zero, reveals the power law exponent of exponential functions; see the text, and Eqs (1) and (2). (B) At high cell density, NCFU of the wild type cells plotted as described above follows a straight line with a slope of 1, indicating that the survival kinetics can be described by Eq. (1); see also S7A Fig for another high cell density. (C-D) At lower cell density (see also S7C Fig—S7E Fig for other low cell densities), the slope is initially 2 (green region), but becomes 1 later, revealing the biphasic decay seen in Fig. 1. The time at which the transition occurs is marked as T0 (arrows). Numerically, T0 is obtained from the time point at which the orange line and the cyan dashed line intersect. Note that T0 is greater for lower density. (E) T0−1 is linearly proportional to N0. (F, G) We obtained the coefficients c1 and c2 in Eqs (1) and (2) by fitting the second phase and the first phase of the biphasic decay respectively. Note that for high cell densities which show a single-phase decay, we used Eq. (1) to fit the entire range, and c2 is not available. We see that c2 increases linearly to N0 (c2 ∝ N0) in Fig. 3F. In Fig. 3G, we see c1 remains constant for different N0. The dashed lines are plotted for a visual guide.