Isolation and partial characterization of a plasmid in the extremely halophilic archaebacterium Halococcus morrhuae CCM 537

The extremely halophilic archaebacterium Halococcus morrhuae CCM 537 was found to contain’’ a plasmid, pHM2, of 6.0 kb. A restriction map was constructed. Southern hybridization of pHM2 DNA to DNA extracted from other Halococcus sp. strains revealed the presence of a similar plasmid in one other strain. A plasmid of Halobacterium trapanicum shared common sequences with pHM2. Other plasmids from halobacteria displayed no homology with pHM2. The characterization of pHM2 may make it useful for the development of cloning vectors for extremely halophilic archaebacteria.