Green sulfur bacteria
Green sulfur bacteria are nonmotile (except Chloroherpeton thalassium, which may glide) and occur in spheres, rods, and spirals. Photosynthesis is achieved using a Type 2 Reaction Centre using bacteriochlorophyll (BChl) a and in chlorosomes which employ BChl c, d, or e; in addition chlorophyll a is also present,. They use sulfide ions, hydrogen or ferrous iron as an electron donor and the process is mediated by the type I reaction centre and Fenna-Matthews-Olson complex. Elemental sulfur deposited outside the cell may be further oxidized. By contrast, the photosynthesis in plants uses water as the electron donor and produces oxygen.
Chlorobium tepidum has emerged as a model organism for the group; although only 10 genomes have been sequenced, these are quite comprehensive of the family's biodiversity. Their 2-3 Mb genomes encode 1750-2800 genes, 1400-1500 of which are common to all strains. The apparent absence of two-component histidine-kinases and response regulators suggest limited phenotypic plasticity. Their small dependence on organic molecule transporters and transcription factors also indicate these organisms are adapted to a narrow range of energy-limited conditions, an ecology shared with the simpler cyanobacteria, Prochlorococcus and Synechococcus
A species of green sulfur bacteria has been found living near a black smoker off the coast of Mexico at a depth of 2,500 m in the Pacific Ocean. At this depth, the bacterium, designated GSB1, lives off the dim glow of the thermal vent since no sunlight can penetrate to that depth.
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LSPN)   and the phylogeny is based on 16S rRNA-based LTP release 111 by The All-Species Living Tree Project 
♪ Prokaryotes where no pure (axenic) cultures are isolated or available, i. e. not cultivated or can not be sustained in culture for more than a few serial passages
♦ Type strain lost or not available
♥ Strains not lodged at National Center for Biotechnology Information (NCBI) or listed in the List of Prokaryotic names with Standing in Nomenclature (LPSN)
♠ Strains found at the National Center for Biotechnology Information (NCBI) but not listed in the List of Prokaryotic names with Standing in Nomenclature (LSPN)
- D.A. Bryant & N.-U. Frigaard; Frigaard (November 2006). "Prokaryotic photosynthesis and hototrophy illuminated". Trends Microbiol. 14 (11): 488–96. PMID 16997562. doi:10.1016/j.tim.2006.09.001.
- Beatty JT, Overmann J, Lince MT, Manske AK, Lang AS, Blankenship RE, Van Dover CL, Martinson TA, Plumley FG.; Overmann; Lince; Manske; Lang; Blankenship; Van Dover; Martinson; Plumley (2005). "An obligately photosynthetic bacterial anaerobe from a deep-sea hydrothermal vent". Proc. Natl Acad. Sci. USA 102 (26): 9306–10. PMC 1166624. PMID 15967984. doi:10.1073/pnas.0503674102.
- Crowe, Sean; Jones, CarriAyne; Katsev, Sergei; O'Neill, AH; Sturm, A; Canfield, DE; Haffner, GD et al. (2008). "Photoferrotrophs thrive in an Archean Ocean analogue". Proceedings of the National Academy of Sciences 105 (41) (2008-10-14). pp. 15938–43. ISSN 0148-0227. PMC 2572968. PMID 18838679. doi:10.1073/pnas.0805313105. Retrieved 2009-06-30.
- See the List of Prokaryotic names with Standing in Nomenclature. Data extracted from J.P. Euzéby. "Chlorobi". Retrieved 2013-03-20.
- See the NCBI webpage on Chlorobi Data extracted from Sayers et al. "NCBI Taxonomy Browser". National Center for Biotechnology Information. Retrieved 2013-03-20.
- See the All-Species Living Tree Project . Data extracted from the "16S rRNA-based LTP release 111 (full tree)" (PDF). Silva Comprehensive Ribosomal RNA Database. Retrieved 2013-03-20.
- "The Family Chlorobiaceae". The Prokaryotes. Retrieved July 5, 2005.