| Summary: | In the pursuit of cultivating anaerobic anoxygenic phototrophs with unusual absorbance spectra, a purple sulfur bacterium was isolated from the shoreline of Baltrum, a North Sea island of Germany. It was designated strain 970, due to a predominant light harvesting complex (LH) absorption maximum at 963–966 nm, which represents the furthest infrared-shift documented for such complexes containing bacteriochlorophyll <i>a</i>. A polyphasic approach to bacterial systematics was performed, comparing genomic, biochemical, and physiological properties. Strain 970 is related to <i>Thiorhodovibrio winogradskyi</i> DSM 6702<sup>T</sup> by 26.5, 81.9, and 98.0% similarity via dDDH, ANI, and 16S rRNA gene comparisons, respectively. The photosynthetic properties of strain 970 were unlike other <i>Thiorhodovibrio</i> spp., which contained typical LH absorbing characteristics of 800–870 nm, as well as a newly discovered absorption band at 908 nm. Strain 970 also had a different photosynthetic operon composition. Upon genomic comparisons with the original <i>Thiorhodovibrio</i> strains DSM 6702<sup>T</sup> and strain 06511, the latter was found to be divergent, with 25.3, 79.1, and 97.5% similarity via dDDH, ANI, and 16S rRNA gene homology to <i>Trv. winogradskyi</i>, respectively. Strain 06511 (=DSM 116345<sup>T</sup>) is thereby described as <i>Thiorhodovibrio litoralis</i> sp. nov., and the unique strain 970 (=DSM 111777<sup>T</sup>) as <i>Thiorhodovibrio frisius</i> sp. nov.
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