TABLE 2.

Expression of an oprM-lacZ fusion in MexAB OprM⁺ and MexAB OprM⁻ P. aeruginosa^a

Strain	Plasmid	β-Galactosidase activity (Miller units)b
PAO6609	pMP190	16.2 ± 2.9
PAO6609	pRSP43	83.2 ± 6.0
PAO6609	pRSP44	12.4 ± 1.5
K1032	pMP190	17.4 ± 3.1
K1032	pRSP43	73.4 ± 3.6
K1032	pRSP44	6.9 ± 0.5

^aP. aeruginosa PAO6609 (MexAB OprM⁺) and K1032 (ΔmexAB oprM) carrying pMP190 or the oprM-lacZ pMP190 derivatives pRSP43 and pRSP44 were cultured in LB broth with appropriate antibiotic to an A₆₀₀ of 1.0 and assayed for β-galactosidase activity as described in Materials and Methods. 

^bValues are means of two separate experiments performed in triplicate ± standard deviations.