FIG. 3.

Southern blot of chromosomal DNA from strains 3720 (lane 1), 3720R9 (lane 2), and 3720R9.2 (lane 3). DNAs were digested with BclI. The radioactive probe used was the insert of pJSE2001 excised as a HindIII/XbaI fragment and labeled by random priming. The figure shows that 3720R9 contains a fragment that is larger than the insert of pJSE2001 by about 1.4 kb (the size of the ermE gene minus the size of the BglII fragment of pJSE2001) and that strain 3720R9.2 contains both this fragment and a second one whose size corresponds to that predicted for pJSE2089. That the band corresponding in size to pJSE2089 is less intense than the band below it is probably due to incomplete transfer of the former band to the Southern filter. Lane 4 contains a series of molecular weight markers of 9.3, 6.8, 4.4, 2.7, 1.5, and 0.85 kb.