Fate of transforming deoxyribonucleic acid after uptake by competent Bacillus subtilis: size and distribution of the integrated donor segments.

A series of sheared donor-recipient complex samples were prepared from a competent Bacillus subtilis culture which had been transformed by using (3)H, (2)H-labeled deoxyribonucleic acid. Measurement of the molecular weights and buoyant densities of these samples led to the following conclusions. (i) The average size of the single-stranded donor segment which is integrated is 2.8 x 10(6). (ii) These donor segments are not randomly distributed in the recipient genome, but are clustered in groups, each group containing several discrete donor segments.