Table 2.

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 + Tet
pUC19	2.22 × 109	2.25 × 109	0
pUC19:tetA	4.2 × 109	0	2.85 × 109
pET23a	2.85 × 109	2.39 × 109	0
pET23a:tetA	2.03 × 109	0	2.11 × 109

Disruptants were created by cloning a tetracycline 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 tetracycline. cfu; colony forming unit.