Haloarcula spp able to biosynthesize exo- and endopolymers

Three halobacteria strains (T5, T6, T7), growing optimally at a sodium chlo ride concentration of 3.5 M, were isolated from samples collected in the Tu nisian marine saltern located close to Monastir. Although they were differe nt in colony and cell morphology, the isolates were similar in most respect s and all produced a homopolyester identified spectroscopically as polyhydr oxybutyrate when grown on carbohydrates. Under the same conditions, the iso lates formed acidic exopolysaccharides. Acid methanolysis of their complex lipids released archaeol (2,3-di-O-phytanyl-sn-glycerol). All the isolates had polar lipid patterns characteristic of representatives of the genus Hal oarcula. Partial sequence analysis of 16S rRNA genes from strain T5 confirm ed its assignment to the genus Haloarcula. Although strain T5 differed phen otypically from the species Haloarcula japonica in several respects, DNA-DN A hybridization indicated that the T5 isolate is a new strain of H. japonic a.