PHYLOGENETIC STUDY OF HALOANAEROBIC BACTERIA BY 16S RIBOSOMAL-RNA SEQUENCES ANALYSIS

The nucleotide sequences of 16S rRNA of four strains of the haloanaero bic bacteria Haloincola saccharolytica Acetohalobium arabaticum, Halob acteroides lacumaris, and Halobacteroides sp. have been determined. Th e phylogenetic analysis employing the MTP method placed the group of t he haloanaerobes in a single cluster at the base of a branch leading t o the Gram-positive organisms on the constructed unrooted tree. Howeve r, an additional analysis demonstrated that the cluster of the haloana erobes did not belong to any subdivision of Gram-positive bacteria, in cluding the representatives of the Gram-negative branches - Heliobacte rium and Sporomusa. The signature analysis and the secondary structure analysis of the 16S rRNA of the haloanaerobes revealed some peculiari ties that distinguish them from the other bacterial phyla. All these d ata along with the unique phenotype of these microorganisms demonstrat e that the haloanaerobes represent a separate line of descent within t he Bacteria.