Physical map of the Bacillus subtilis replication terminus region: its confirmation, extension and genetic...

The library of Bacillus subtilis DNA previously cloned in the cosmid vector pHC79 has been screened for the replication terminus region using a higher level of terminus probe. 24 of 48 recombinant cosmids which gave a positive response had restriction fragment compositions consistent with their inserts originating from or extending into the terminus region for which a 150-kb restriction map has already been constructed (Weiss and Wake, 1983). DNA spanning terC, the site of termination, appears to be missing from the library, although DNA to either side of terC has been cloned. A detailed analysis of four of the newly identified recombinant cosmids has confirmed most of the previous 150-kb map and allowed it to be extended to 180 kb. Physical linkage of the two cosmid inserts that most closely approach terC on each side has been demonstrated. The location of the genetic marker gltA and the orientation of the restriction map relative to the genetic map of the B. subtilis chromosome have also been established.