Purple sulfur bacteria
The purple sulfur bacteria or Chromatiaceae are a group of anaerobic or microaerophilic photosynthetic Gram negative bacteria which express a variety of pigments, including yellow and red carotenoids and bacteriochlorophylls a and b which can combine to form purple, red, brown, or orange colorations.The bacteria are often found in sulfur springs and stagnant water.
They are alike in that they use hydrogen sulfide as a primary electron donor, and the process of oxidation of hydrogen sulfide results in the production of intracellular elemental sulfur granules. The oxidation of this elemental sulfur to sulfuric acid is used for energy production.
Example species include Chromatium vinosum, Thispirillum jenense, and Thiopedia rosea.
See also: purple non-sulfur bacteria