Characterization of the natural deletion mutant of plasmid pXZ10145 in Corynebacterium glutamicum and construction of a recombinant plasmid.

Plasmid pNAT65, carrying the chloramphenicol resistance marker, was chosen from a number of natural deletion mutants of pXZ10145 when pXZ10145 DNA, originally isolated from Corynebacterium glutamicum 1014-6T, was used to transform the protoplast of Corynebacterium crenatum T6-13. The size of pNAT65 was 2.4 kb, determined by electrophoresis on 0.7% agarose gel. The physical map of plasmid pNAT65 was determined. One recombinant plasmid, pNAR67, was constructed with the DNA fragments of pNAT65 and pBR322 digested respectively with EcoRI. This plasmid was capable of replication in E. coli, expressing ampicillin and tetracycline resistance; but with lower chloramphenicol, the resistance was only about 2 micrograms/ml.