Purple non-sulfur bacteria are some of the most metabolically versatile organisms known. Rhodobacter sphaeroides, Rhodospirillum rubrum, Rhodopseudomonas palustris, etc.can use light as a source of energy (anoxygenic phototrophy) or organic and inorganic compounds as electron donors and acceptors (respiratory and fermentative growth). In addition, these bacteria are also able to use a very large spectrum of carbon sources ranging from carbon dioxide (autotrophic growth) to fermentative products generated by other organisms in the same habitat (heterotrophic growth)
