Rhodospirillum is group of purple nonsulfur photosynthetic bacteria which includes Rhodopseudomonas. Purple nonsulfur bacteria belong to the class of α-proteobacteria which are capable of growing at low nutrient levels. Normally they grow anaerobically trapping light energy and employing organic molecules as carbon sources, but they also can grow aerobically in the dark. Although they are called nonsulfur bacteria, some species can utilize sulfides.
Rhodospirillum is a genus of gram-negative, spiral bacteria that possesses internal photosynthetic membranes. Its organisms divide by binary fission, are motile by means of polar flagella, and are found in aquatic environments. The genus includes Rhodospirillum rubrum and Rhodospirillum centenum. R. rubrum is a vibrio- to spiral-shaped phototrophic bacteria found in stagnant water and mud exposed to light. R. centenum is a thermotolerant, cyst-forming, anoxygenic photosynthetic species. 2
- Microbiology. Lansing M. Prescott, John P.Harley, Donald A. Klein