RECLASSIFICATION OF SPECIES OF THE SPIRAL-SHAPED PHOTOTROPHIC PURPLE NONSULFUR BACTERIA OF THE ALPHA-PROTEOBACTERIA - DESCRIPTION OF THE NEW GENERA PHAEOSPIRILLUM GEN. NOV., RHODOVIBRIO GEN. NOV., RHODOTHALASSIUM GEN. NOV. AND ROSEOSPIRA GEN. NOV. AS WELL AS TRANSFER OF RHODOSPIRILLUM-FULVUM TO PHAEOSPIRILLUM-FULVUM COMB. NOV., OF RHODOSPIRILLUM-MOLISCHIANUM TO PHAEOSPIRILLUM-MOLISCHIANUM COMB. NOV., OF RHODOSPIRILLUM-SALINARUM TO RHODOVIBRIO-SALINARUM

The 16S rDNA sequence of Rhodospirillum mediosalinum was determined an d compared with corresponding sequences from other spiral-shaped purpl e non-sulfur bacteria classified as or related to the genus Rhodospiri llum in the cc subclass of the Proteobacteria. Sequence similarities s eparate the currently recognized Rhodospirillum species into five diff erent groups with no more than 91% sequence similarity, clearly indica ting the necessity to recognize these groups as different genera. Majo r diagnostic properties of these bacteria are compared and new genera Phaeospirillum gen. nov., Roseospira gen. nov., Rhodothalassium gen. n ov. and Rhodovibrio gen. nov, are described with the species Phaeospir illum fulvum comb, nov., Phaeospirillum molischianum comb. nov., Rhodo vibrio salinarum comb. nov., Rhodovibrio sodomensis comb. nov., Rhodot halassium salexigens comb. nov. and Roseospira mediosalina comb. nov. The genus Rhodospirillum is represented by Rhodospirillum rubrum and R hodospirillum photometricum and an emended description of this genus i s also given.