Southern hybridization of the rarA operon. Schematic representations of the regions surrounding the rarA operon are shown. The intact rarA gene in strain 17B or the split rarA fragments in strain Beluga are shaded. The probe used in the accompanying Southern blot (lane 1, 17B; lane 2, Beluga; and lane 3, CDC66177) targeted either the intact rarA gene in strain 17B or the larger rarA fragment (indicated by an asterisk) in strain Beluga. XbaI restriction sites are indicated by a red line and expected fragment sizes are shown.