TABLE 4.

LasR- and RhlR-dependent expression of the hcnA promoter of P. aeruginosa in P. fluorescens CHA0^a

Plasmids	Regulator present	β-Galactosidase activity (Miller units)
		No addition	+BHL	+OdDHL
pME3837 + pME6001		103 ± 17	ND	ND
pME3837 + pME3840	RhlRI	421 ± 32	452 ± 36	ND
pME3837 + pME3827	LasR	94 ± 5	ND	441 ± 36
pME3844 + pME3827	LasR	62 ± 3	ND	89 ± 7
pME3844 + pME3840	RhlRI	60 ± 6	69 ± 4	68 ± 5

^aThe hcnA′-′lacZ fusion constructs pME3837 and pME3844 (Fig. 6) were tested in strain CHA0. Cells were grown in 40 ml of MMC (in 100-ml Erlenmeyer flask) at 30°C with shaking to an OD₆₀₀ of 1.0 to 1.2. BHL was dissolved in 15% acetonitrile and added at a concentration of 10 μM; OdDHL was dissolved in 50% acetonitrile and added at a concentration of 50 nM. β-Galactosidase activities were determined in triplicate; means ± standard deviations are given. ND, not determined.