Table 1. Induction of the SOS response at the population level, in persister cells and in sensitive cells throughout microfluidic time-lapse experiments.

Mean fluorescence and SDs for the wild-type strain containing the psulA::gfp reporter plasmid during time-lapse microscopy in the microfluidic chamber for the bulk of the population, the 23 persister cells and a subset of 14 random nonpersister cells (see Materials and Methods for how the random subset of cells was defined) at indicated times. In the case of persister cells early recovery, the maximum value of fluorescence was used and therefore corresponds to different times of recovery. The indicated time corresponds to the mean time at which persister cells reached maximum fluorescence together with the corresponding SD. The fourth column represents the mean fluorescence fold increase as compared to the untreated condition. The fifth column represents the number of cells that were analyzed. The sixth column represents the QCV, i.e., the interquartile range divided by the median, and is a robust measurement of heterogeneity within a sample (see Materials and Methods). AU, arbitrary units.

	Time	Mean fluorescence (AU/μm2 × 103)	Fold increase	Sample size	QCV (%)
Population	6 hours of growth	0.29 ± 0.16		14,946	22.3
	5 hours of ofloxacin	3.69 ± 2.49	12.6	20,022	79.2
	3.5 hours of recovery	3.54 ± 3.40	12.1	18,027	90.5
	8.5 hours of recovery	3.03 ± 3.71	10.4	16,448	101.3
Persister cells	6 hours of growth	0.30 ± 0.09		23	36.0
	5 hours of ofloxacin	4.39 ± 2.69	14.9	23	104.5
	3.6 ± 2.4 hours of recovery	7.28 ± 3.95	24.7	23	85.9
	8.5 hours of recovery	2.21 ± 1.26	7.5	23	75.9
Sensitive cells	6 hours of growth	0.35 ± 0.16		14	44.2
	5 hours of ofloxacin	3.42 ± 3.11	9.6	14	91.3
	3.5 hours of recovery	3.22 ± 3.37	9.1	14	88.5
	8.5 hours of recovery	2.97 ± 2.98	8.4	14	83.7