Characterization of a high molecular mass resistance plasmid isolated from Klebsiella pneumoniae and coding for lactose degradation

Abstract Originated from Klebsiella pneumoniae , pCL300 is a self-transmissible plasmid, coding for multiple antibiotic resistances and for lactose degradation. This fi⁺ plasmid belongs to the incompatibility group F I and is stably maintained in various lactose-negative Escherichia coli or in Salmonella typhi . The molecular mass determined by agarose gel electrophoresis after endonuclease digestions and confirmed by the electron microscope was 243 ± 15 kb, an unusually high value for a plasmid belonging to the incF I group.