Plasmid transformation in Bacillus subtilis: effects of insertion of Bacillus subtilis DNA into plasmid pC194

We have constructed a hybrid plasmid pBC1, which consists of plasmid pC194 with an insert of B. subtilis DNA as its HindIII restriction site. This plasmid is stably maintained in B. subtilis. In contrast with pC194, monomeric ccc forms of pBC1 are active in transformation. Transformations with these monomeric molecules of pBC1 have a stringent requirement for recombination proficiency, as defined by recE in the recipient cell. The extent of dependence of the transforming activity of oligomeric pBC1 DNA on the recombination proficiency of the recipient cell decreases with increasing oligomer size. A model of DNA processing during plasmid transformation of B. subtilis is presented.