Green sulfur bacteria
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Chlorobium |
The green sulfur bacteria (Chlorobiaceae) are a family of phototrophic bacteria. No other bacterial families are known to be closely related to them, and they are accordingly placed in their own phylum (Chlorobi). The phylum is most closely related to Bacteroidetes.
Green sulfur bacteria are generally nonmotile (one species has a flagellum), and come in spheres, rods, and spirals. Their environment must be oxygen-free, and they need light to grow. They engage in photosynthesis, using bacteriochlorophylls c, d, and e in vesicles called chlorosomes attached to the membrane. They use sulfide ions as electron donor, and in the process the sulfide gets oxidized, producing globules of elemental sulfur outside the cell, which may then be further oxidized. (By contrast, the photosynthesis in plants uses water as electron donor and produces oxygen.)
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 meters beneath the surface of the Pacific Ocean. At this depth, the bacteria, designated GSB1, lives off the dim glow of the thermal vent since no sunlight can penetrate to that depth.
[edit] References
- Beatty JT, Overmann J, Lince MT, Manske AK, Lang AS, Blankenship RE, Van Dover CL, Martinson TA, Plumley FG. (2005). "An obligately photosynthetic bacterial anaerobe from a deep-sea hydrothermal vent". Proceedings of the National Academy of Sciences 102 (26): 9306-10. PMID 15967984.
[edit] External link
- The Family Chlorobiaceae. The Prokaryotes. Retrieved on July 5, 2005.
