[RecA-independent induction of the new plasmid rAS1 after introduction of a fragment of the cryptic plasmid p1414 into Bacillus subtilis 168 cells].

Bacillus subtilis 168 was transformed with fragments from the minireplicon of the cryptic plasmid p1414; these fragments were ligated into the cat gene of plasmid pC194. As a result, the 4.6 kb plasmid pAS1 appeared with a low frequency. The plasmid was homologous to the chromosomal DNA of B. subtilis 168, but had no homology with p1414. Plasmid pAS1 had extensive homology (3.2 kb) with plasmid pUB110 and its restriction map in this region of homology correlated well with the restriction map of pUB110. Plasmid pAS1 occurred both in rec+ and recA- cells. We suppose that pAS1 was generated because of the illegitimate recombination between p1414 and the replicon pUB110 incorporated in the chromosome of B. subtilis 168, and the resulting substitution of marker KmR of pUB110 for marker CmR of pC194.