Table 1.

The primary P. aeruginosa signal molecules show a robust near twofold difference in decay rate across a diverse set of growth environments

Environment	Decay Constants, h−1 (95% CI)		Ratio	P value
	3-Oxo-C12-HSL	C4-HSL
BHI	0.34–0.39	0.17–0.22	1.87	7.3E−15
KB	0.04–0.05	0.02–0.03	1.70	6.0E−13
LB	0.07–0.08	0.04–0.05	1.69	4.4E−11
M9	0.15–0.17	0.09–0.10	1.66	3.4E−18

The absolute decay rates of 3-oxo-C12-HSL and C4-HSL vary nearly 10-fold across environments, but the rates are tightly correlated between signals, so that C4-HSL is consistently around 1.7-fold more fragile. Decay constants were measured across rich laboratory growth media, plus a defined minimal medium: BHI, KB, LB, and M9, respectively (See SI Text, Signal Half-Life Experiments). Decay rates are represented as the 95% confidence intervals (CI) of proportional decay per hour. The P values indicate a significant difference between the decay rates of 3-oxo-C12-HSL and C4-HSL in that environment (ANOVA Interaction term in a log-linear model). Decay rates were measured using engineered bioreporters, the luminescence of which indicated the concentration of an AHL solution compared with a calibration of known concentrations (Figs. S4 and S5).