Effect of the deletion of a fragment dispensable for the autonomous maintenance of plasmid pT181 on the competition between incompatible plasmids.

The deletion of the 560-bp HindIII C fragment from pT181 derivatives does not change the stability or copy number of the plasmid but affects its ability to compete with undeleted, incompatible plasmids for maintenance in the host cell. The disadvantage of the deleted plasmids seems to be manifested at the level of replication. It results that for plasmid pT181 a sequence dispensable for autonomous maintenance and replication control could affect the outcome of the competition between autonomous, incompatible plasmids.