Deoxyribonucleic acid reiatedness among species of Haloarcula and other halobacteria

Abstract

Several representative strains of Haloarcula vallismortis, Haloarcula hispanica, and other Haloarcula species not currently accepted as valid species were examined for genetic relatedness to each other and to members of other halobacterial species. The G + C content of DNA of the 11 strains of the genus Haloarcula tested ranged between 56.9 and 66.3 mol%. The G + C contents obtained for Haloarcula vallismortis and Haloarcula hispanica were 56.9–64.3 mol%, and 58.7–66.3 mol%, respectively. The results of our DNA–DNA hybridization experiments indicate that Haloarcula vallismortis and Haloarcula hispanica are composed of strains with high DNA homology, constituting genotypic species that correlate with the previously reported phenotypic features. However, our results do not support the separation of "Haloarcula californiae," "Haloarcula sinaiiensis," "Halobacterium marismortui," and "Amoebobacter morrhuae" in different taxonomic taxa, since high DNA homology was obtained between these strains and representatives of species of the genus Haloarcula.Key words: archaebacteria, halobacteria, Haloarcula, DNA homology, nucleic acids hybridization.