Plasmid transformation in Bacillus subtilis. The significance of partial homology between plasmid and recipient cell DNAs.

A series of hybrid plasmids consisting of pC194 or pUB112 and B. subtilis DNA were constructed. In contrast to plasmid pC194, purified monomeric forms of such plasmids were active in transformation, provided the recipient cells were recombination proficient. Similarly the monomers of pC194 derived plasmids, containing bacteriophage phi 105 DNA were able to transform phi 105 lysogenic but not nonlysogenic cells. From the results it is concluded that the presence of DNA/DNA homology between chromosomal DNA of the recipient cell and part of the hybrid plasmids used is a sufficient condition to endow monomeric plasmids with transforming activity.