CHEF gel and Southern hybridization analysis of transconjugants obtained from filter mating experiments employing mutant P101D12 as the donor and OG1RF as the recipient. (A) CHEF gel of I-ceuI-restricted DNA from three primary transconjugants, POTC-1, POTC-2, and POTC-3 (lanes 1, 2, and 3, respectively); donor strain P101D12 (lane 4); and recipient strain OG1RF (lane 5). (B and C) Also shown are Southern hybridization analyses of I-ceuI-restricted DNA from the transconjugants (lanes 1 to 3), donor strain P101D12 (lane 4), and recipient strain OG1RF (lane 5) using a 23S rRNA gene probe (B) and a Tn917-specific probe (C). Bacteriophage lambda concatemers were used as molecular size markers (lane M; New England Biolabs, Beverly, MA).