Plasmid transformation in Bacillus subtilis. Alterations introduced into the recipient-homologous DNA of hybrid plasmids can be corrected in transformation.

Various alterations (deletions, additions, inversions) were introduced into portions of pC194/B. subtilis or pC194/phi 105 hybrid plasmid molecules which are homologous to the DNA of recipients in transformation. These plasmids are stably maintained in transformations of recombination deficient cells. In transformations of recombination proficient cells, they can be corrected to those plasmid forms into which the alterations were originally introduced. This correction is most pronounced when transformations are performed with monomeric ccc forms of hybrid plasmids. It is suggested that correction is a consequence of mismatch repair occurring in the synapsis of homologous portions of plasmid and resident DNAs.