Recombination between repeated DNA sequences occurs more often in plasmids than in the chromosome of Bacillus subtilis.

Directly repeated pBR322 sequences 3.7-3.8 kb long recombine with a frequency of about 10% per generation when carried on plasmids related to pC194 and 0.01% per generation when carried on the Bacillus subtilis chromosome. Recombination is therefore 1,000 times more efficient in plasmids than in the chromosome of this organism.