TABLE 5.

Influence of tcpA and tol mutations on CTXφ transfer in a coculture transduction assay^a

Recipientb	Mutant gene(s)	No. of recipients/ml	No. of Kanr recipients/ml	Frequency of infectionc
O395	Wild type	2.2 × 109	6.3 × 107	2.9 × 10−2
TCP2	tcpA	2.1 × 109	1.6 × 103	7.6 × 10−7
DH1	tolQ	1.1 × 109	2.9 × 103	2.6 × 10−6
DH5	tcpA and tolQ	4.9 × 108	0	0
DH2	tolR	7.5 × 108	2.1 × 103	2.8 × 10−6
DH6	tcpA and tolR	1.3 × 108	0	0
DH3	tolA	7.1 × 108	4.4 × 102	6.2 × 10−7
DH7	tcpA and tolA	1.2 × 108	0	0
DH4	tolB	2.2 × 108	2.2 × 107	1.0 × 10−1

^aDonor strain RV508 (pCTX-Kn) was cross-streaked with the indicated recipient strain on LB agar plates. Transfer of CTX-Knφ to the recipient was then measured after 4.5 h. These assays were conducted at least three times, and the mean number of CFU from these experiments is presented. The standard deviation of these values was less than 10% of the means. 

^bAll recipient strains are derivatives of O395. 

^cFrequency of infection was calculated by dividing the number of Kn^r recipients by the total number of recipients. The ratio of donors (no. of Spec^r Rif^r CFU) to recipients was constant for each assay.