Table 4.

Viable transformant counts of E. coli transformants carrying vectors with an undisrupted or disrupted ampicillin selectable marker

	Viable transformant count (cfu/ml) on medium
Transformant	LB	LB + Amp	LB + Kan
pUC19	2.22 × 109	2.25 × 109	0
pUC19:kanR	6.7 × 108	0	7.3 × 108
pBlueScript	2.87 × 109	2.81 × 109	0
pBlueScript:kanR	2.05 × 109	0	1.78 × 109

Disruptants were created by cloning a kanamycin selectable marker gene into a unique restriction site in the vector encoded ampicillin resistance gene. Transformants were plated onto LB medium supplemented with either ampicillin or kanamycin. cfu; colony forming unit.