TABLE 1.

Bacterial strains and plasmids used in this study

Strain or plasmid	Characteristics	Source or reference
E. coli strains
XLOLR	Recipient of λ-ZAP II vector; chlorhexidine sensitive	Stratagene
S17-1/λpir	Donor of pUTKm1 Δtnp Δbla Δmini-Tn5 during conjugation; ampicillin sensitive	7
ATCC 25922	Chlorhexidine sensitive and ampicillin sensitive	American Type Culture Collection
Plasmids
pBK-CMV	Phagemid vector resulting from in vivo excision of λ-ZAP II vector in E. coli XLOLR	Stratagene
pUTKm1 Δtnp Δbla     Δmini-Tn5	Suicide vector constructed from pUTKm1 by deleting tnp, bla, and mini-Tn5 transposon through restriction enzymatic digestion (SalI, ApaLI, and EcoRI, respectively) followed by ligation	This work
pCRII-TOPO	TA cloning vector	Invitrogen