TABLE 2.
Frequency of mobilization of Salmonella plasmids in conjugationa
| F′ donor | pSV size (kb) | Frequency of transconjugant formation
|
|||
|---|---|---|---|---|---|
| Expt 1 | Expt 2 | Expt 1 | Expt 2 | ||
| Pullorum plasmids | |||||
| Sp F′ lac+/pOU1401 | 91.7 | 0.51 × 10−3 | 1.09 × 10−3 | ||
| Ec F′ lac+/pOU1401 | 91.7 | 2.45 × 10−4 | 3.13 × 10−4 | ||
| Sp F′ lac+/pOU1506 | 14.1 | 0.90 × 10−2 | 1.36 × 10−2 | ||
| Ec F′ lac+/pOU1506 | 14.1 | 3.15 × 10−3 | 3.74 × 10−3 | ||
| Sp F′ lac+/pOU1507 | 5.4 | 5.67 × 10−1 | 8.9 × 10−1 | ||
| Ec F′ lac+/pOU1507 | 5.4 | 4.12 × 10−2 | 6.03 × 10−2 | ||
| Enteritidis plasmids | |||||
| Se F′ lac+/pOU1204 | 65.8 | 9.21 × 10−5 | 8.92 × 10−5 | ||
| Ec F′ lac+/pOU1204 | 65.8 | 7.32 × 10−5 | 8.91 × 10−5 | ||
| Se F′ lac+/pOU1504 | 10.8 | 1.40 × 10−2 | 1.61 × 10−2 | ||
| Ec F′ lac+/pOU1504 | 10.8 | 4.23 × 10−3 | 6.12 × 10−3 | ||
| Typhimurium plasmids | |||||
| St F′ lac+/pOU206 | 98.5 | 1.33 × 10−4 | 5.96 × 10−4 | ||
| Ec F′ lac+/pOU206 | 98.5 | 1.03 × 10−5 | 3.02 × 10−5 | ||
| St F′ lac+/pOU1505 | 5.1 | 4.01 × 10−3 | 5.4 × 10−3 | ||
| Ec F′ lac+/pOU1505 | 5.1 | 1.80 × 10−4 | 3.16 × 10−4 | ||
E. coli HB101 was used as the recipient. Sp, serovar Pullorum OU7351; Ec, E. coli DH5α; Se, serovar Enteritidis OU7044; St, serovar Typhimurium OU5048. Mobilization of pUC18, whether in a Salmonella or E. coli host as the donor strain, was nil. All donors harbored F′ lac+, which was used to mobilize the Salmonella plasmid. The F′ lac+ donor that contained the Salmonella plasmid (first column) was mixed with the recipient for mating as described in Materials and Methods, and the frequency of Salmonella plasmid transconjugant formation was measured. Matings were repeated three to five times. The mating frequency varied greatly from one experiment to another with the same donors because of subtle differences in growth stage, aeration, and donor-to-recipient ratio in each mating, but the trend was consistent. Therefore, only two representative mating experiments are shown here. In each experiment, the transfer frequency of the F′ lac+ plasmid was similar regardless of the presence or absence of Salmonella plasmids in the F′ donor, and therefore its frequency, as high as 100% in overnight matings, is not shown.