TABLE 3.

Phenotypic analysis of SXT deletions

Deletiona	Region deleted	SXT transfer (10−4)b	CloDF13 transfer (10−4)c	Circle formationd	R391 complementatione
WT		1.0	3.2	+	NA
Δ1	′rumB-rumA	8.0	4.6	+	NA
Δ2	s024-s040	1.7	1.0	+	NA
Δ3	tral	UD	0.1	+	+
Δ4	traD-s043	UD	5.6	+	−
Δ5	traD	UD	13	+	+
Δ6	s043	UD	22	+	+
Δ7	s044-s045	0.6	10	+	NA
Δ8	traL-traA	UD	UD	+	+
Δ9	s052-traN	UD	UD	+	+
Δ10	s060-s073	0.0064	UD	+	NA
Δ11	s074	0.52	0.75	+	NA
Δ12	traG	UD	UD	+	+
Δ13	s079-s084	UD	UD	−	+
Δ14	setD	UD	UD	−	+f
Δ15	setC	UD	UD	−	+f

^aAll strains are derivatives of BW25113 (7) containing SXT except Δ3, which is a derivative of MG1655. WT, wild type.

^bSXT transfer frequency was calculated as the number of transconjugants observed per donor cell. UD (undetected) is defined as below the limits of detection of the assay (∼10⁻⁸).

^cMating assays were performed as described in note b, but donor cells contained CloDF13. The CloDF13 transfer frequency was calculated as the number of CloDF13 transconjugants observed per donor cell.

^dPCR for detection of a circularized, extrachromosomal form of the element was performed as described previously (15). +, detected; −, not detected.

^eR391 complementation was carried out only for strains that were unable to mobilize SXT. NA, not applicable. +, complementation; −, no complementation.

^fComplementation was performed with plasmids expressing the single gene product.