Two independent replicons can support replication of the anthrax toxin-encoding plasmid pXO1 of Bacillus anthracis

► Two replicons can independently support replication of the full-length pXO1 plasmid. ► The copy number of the full-length pXO1 plasmid supported by the RepX replicon is approximately one per chromosome. ► The copy number of the full-length pXO1 plasmid supported by the ORFs 14/16 replicon is approximately three per chromosome. ► The copy number of the RepX minireplicon is approximately one per chromosome. ► The copy number of the ORFs 14/16 minireplicon is approximately 15-20 per chromosome.