TABLE 1.

Summary of strain genotypes, phenotypes, and colonization abilities

E. coli strain	flhDC expressiona	Motilityb	Intestine-colonizing abilityc
MG1655 (+IS1) ΔflhD	−	−	Best
MG1655 (−IS1)	+	+	Best
MG1655 (+IS1) ΔmotAB ΔfliC	++	−	Next best
MG1655 (+IS1)	++	++	Worst

^a−, no flhDC expression; +, normal flhDC expression; ++, hyper-flhDC expression.

^b−, nonmotile; +, normally motile; ++, hypermotile.

^cSee Fig. 6.