Table 1. Effects of exogenous PCA on the transcription of two phz gene clusters in Pseudomonas sp. M18 and its two mutants M18ΔP1 and M18ΔP2.

Strains	Without exogenous PCA				With exogenous PCA				Fold
	CTrpoD a	CTphz a	ΔCTc	Z1d	CTrpoD b	CTphz b	ΔCTc	Z2d	Me
M18	16.6±0.1	22.8±0.2	6.2	2.8	17.0±0.5	19.8±0.3	2.8	5.3	10.6
M18ΔP1	16.9±0.3	24.6±0.2	7.7	1.0	16.3±0.3	22.5±0.2	5.2	1.0	5.7
M18ΔP2	17.1±0.1	24.2±0.1	7.1	1.5	16.6±0.2	19.5±0.1	2.9	4.9	18.4

^aValues were measured during exponential phase at an OD₆₀₀ of 2.0 to 2.5. CT, cycle threshold.

^bValues were measured at stationary phase at OD₆₀₀ of 3.5 to 4.0.

^cΔCT = CTphz−CTrpod, CTphz denotes cycle threshold of phzC, phzA2 and phzA1 transcripts in strain M18, M18ΔP1 and M18ΔP2, respectively.

^dZ1 or Z2 = 2^{−Δ(ΔCTphzC-ΔCTphzA2)} (in M18); 2^{−Δ(ΔCTphzA1-ΔCTphzA2)} (in M18ΔP2); 2^{−Δ(ΔCTphzA1-ΔCTphzA2)} (in M18ΔP1), ΔΔCT = ΔCT_low−ΔCT_high (The relative high ΔCT value was defined as 1).

^eM, the increased ratio of expression 2^−ΔΔCT without and with the addition of exogenous PCA in culture. ΔΔCT = ΔCT_with–ΔCT_without.