TABLE 1.

E. coli K-12 strains and plasmids used

Strain or plasmid	Replicon	Genotype and/or phenotypea	Source (reference)
Bacterial strains
CSH50		Δlac-pro rpsL	Miller (9)
TOP10		Lac−	Invitrogen Ltd.
Plasmids
pJL228	p15	CmrprepA-lac+	Light and Molin (6)
pOU16	pBR322	Apr Tcr CopB+	Riise et al. (19)
pOU18	pMB9	Tcr CopB+	Riise et al. (19)
pOU47	R1	Apr Lac+ ParA+	Gerdes et al. (4)

^aFor an explanation of the bacterial designations see reference 1, and for an explanation of the plasmid designations see reference 16.