TABLE 3.

Ara-induced expression of proU P1 from pHYD275 in pHYD408 derivatives of rpoS rho⁺ strains^a

Strain	Chromosomal rpoS genotype	β-Galactosidase sp act with:
		Glu	Ara
GJ2758	rpoS::IS10	17	783
GJ2756	rpoS::Tn10	11	447
GJ2778	ΔrpoS	10	263

^aCultures were incubated in LB medium supplemented with trimethoprim, ampicillin, and either Glu or Ara at 30°C until 1 h after entry into stationary phase for β-galactosidase assays. Enzyme specific activities are reported in Miller units (22).