Figure 5.

Plasmids isolated from Ap^R transductants derived from the supernatant of BD213, which contains a solitary CTX^ET-Ap prophage, are not equivalent to pCTX^ET-Ap. (A) Restriction map of BD213 chromosomal DNA. B, BglII; X, XbaI; E, EcoRI. (B) pCTX^ET-Ap (lanes 5 and 10) yielded different restriction fragments than did plasmid DNA from four transductants (lanes 1–4 and 6–9) after digestion with XbaI (lanes 1–5) and EcoRI/BglII (lanes 6–10). All of the new Ap^R plasmids contained the 5.1-kb BglII fragment and the adjacent Ap^R cassette; all lacked the EcoRI and XbaI sites at the 3′ end of the prophage.