Description of Thiorhodospira
provided by BioPedia
A phototrophic sulfur bacterium isolated from a Siberian soda lake, Thiorhodospira sibirica, genetically related to the genus Ectothiorhodospira. During photolithoautotrophic growth with sulfide as electron donor, the impressively large bacterium forms elemental sulfur globules outside as well as inside the cells. Upon careful microscopic inspection, it can be realized that the sulfur globules associated with the cells are located in the periphery that is represented by an apparently large periplasmic space, but not in the cell interior. Therefore, the mechanism of elemental sulfur formation and the location of the involved enzymes appear to be the same as in species of other Ectothiorhodospiraceae. In the presence of sulfide, organic substances are photoassimilated. Cells are vibrioid or spiral and motile by a monopolar flagellar tuft. Internal photosynthetic membranes are parallel lamellae underlying the cytoplasmic membrane. Photosynthetic pigments are bacteriochlorophyll a and carotenoids of the spirilloxanthin series. Development is dependent on sodium salts in low concentrations and on alkaline conditions. The metabolism is strictly anaerobic and obligately phototrophic.
