Plasmids from Halomonas eurihalina, a microorganism which produces an exopolysaccharide of biotechnological interest

The moderately halophilic bacterium Halomonas eurihalina strain F2-7, able to produce an exopolysaccharide, was found to contain two plasmids named pVE1 and pVE2, of 8.1 and 5.8 kb respectively. We found no evidence for the involvement of these plasmids in the expression of the mucoid phenotype. Restriction maps of both plasmids were constructed. Southern hybridization revealed similarities between them but excluded the existence of sequences homologous to other plasmids isolated from the Halomonas species. Neither pVE1 nor pVE2 displayed any homology with other plasmids isolated from moderate halophiles. The occurrence of similar plasmids in other strains of Halomonas eurihalina, isolated from hypersaline soils, has been detected. These small plasmids may be useful for the development of cloning vectors for moderately halophilic bacteria.