Analysis of total DNA of L. delbrueckii subsp. bulgaricus VI104 transformants by agarose gel electrophoresis (A) and by hybridization with pCU1882 as the probe (B). Total DNA extracted from one transformant (lanes 2) was compared with the following plasmids used for transformation (lanes 1): pGT633 (A) and pCU1882 (B). The arrowheads, the circle, and the star indicate the positions of the covalently closed plasmid monomers, the high-molecular-weight multimers, and the chromosomal DNA, respectively.