Structural instability and stabilization of IncP-1 plasmids integrated into the chromosome of Myxococcus xanthus

Abstract

IncP-1 plasmids are self transmissible to Myxococcus xanthus and maintained integrated into the host chromosome where they are liable to structural instability: deletions can span through the integrated plasmid; the frequency of these events depends on the recipient strain and on the localization of the insertion on the chromosome, but not on the structure of the plasmid. It is possible to isolate stabilized insertion, even from one of the most unstable strains, by growing immobilized cells in carrageenan beads in continuous nonselective culture. The remaining resistant cells are stabilized. Both the structural instability and the possible stabilization of the insertion can be useful when IncP-1 plasmids are used as cloning vectors in Myxococcus xanthus.