TABLE 1.

Bacterial strains and mutator genotypes

Strain	Genotypea	Source of mutator allele
MG1655	Wild type	Coli Genetic Stock Center
CH188	ΔmutS::FRT	This laboratory
CH286	mutY::Tn10dTetr	Jeffrey H. Miller (23)
CH287	damΔ16::Kanr	Martin Marinus (26)
CH289	miaA::ΩCamr	Malcolm Winkler (29)
CH290	ung::Spcr	Murat K. Saparbaev (15)
CH291	mutM::Tn10dTetr	Ashok S. Bhagwat (16)
BS1511	mutA∼ampC::Kanr	M. Zafri Humayun (1)

^a“∼” means the markers are linked by P1 transduction.