REVISION OF THE TAXONOMIC POSITION OF COLORLESS SULFUR SPIRILLA OF THE GENUS THIOSPIRA AND DESCRIPTION OF A NEW SPECIES AQUASPIRILLUM-BIPUNCTATA COMB-NOV

Six strains of gigantic sulfur spirilla, whose characteristics corresp onded to the species diagnoses of Thiospira winogradskii and T. bipunc tata, were shown to belong to the genera of heterotrophic spirilla Aqu aspirillum and Spirillum according to phenotypic properties, nucleotid e composition, and data on DNA homology. Strains D-405, D-409, D-410, D-411, and D-423, which were morphologically similar to T bipunctata, formed a tight cluster according to their phenotypic properties and DN A homology values. These strains were assigned to a new species within the genus Aquaspirillum with the species name A. bipunctata comb. nov . Strain D-427, which perfectly corresponded to the description of the species Thiospira winogradskii, was classified as a representative of the genus Spirillum. The data obtained are used to discuss the tradit ional diagnostic criteria of the genus Thiospira and the taxonomic val idity of this genus.