Table 1.

Transfer of Tn4555 oriT derivatives

ExptPlasmid(s)aSelective mediumbTransfer frequencyc
1pFD576Ap + Sm1.2 × 10−1 ± 1.2
2pFD601Cm + Sm<10−7
3pFD576 + pFD601Ap + Sm2.3 × 10−2 ± 1
4pFD576 + pFD601Cm + Sm3.3 × 10−3 ± 2.4
5pFD576 + pFD601Ap + Cm + Sm2.9 × 10−3 ± 1.7
6pFD576 + pSG335Cm + Sm<10−7 to 4.7 × 10−6d
7pFD576ΔoriT1Ap + Sm5.1 × 10−4 ± 1
8pFD576ΔoriT2Ap + Sm1.9 × 10−4 ± 1.5
9pFD648Ap + Sm<10−7
  • a All matings were triparental matings with a strain containing the plasmids indicated, HB101 (1) as the recipient, and the RK231 conjugation helper strain (5). Matings were performed aerobically as described previously except that incubations were for only 4 h prior to plating on selective medium (28).

  • b Selective medium was L-agar (18) supplemented with the following antibiotics where indicated: streptomycin (Sm), 25 μg/ml; ampicillin (Ap), 50 μg/ml; and chloramphenicol (Cm) 25 μg/ml.

  • c Transfer frequency is the number of transconjugants per input donor cell ± the standard deviation.

  • d Results were variable with this set of plasmids ranging from undetectable to a transfer frequency near the lower end of detectable.