Green sulfur bacteria

Green sulfur bacteria
Green sulfur bacteria in a Winogradsky column
Scientific classification
Domain:	Bacteria
Phylum:	Chlorobi
Class Chlorobea Cavalier-Smith 2002 Order Chlorobiales Gibbons and Murray 1978 Family Chlorobiaceae Copeland 1956 Ancalochloris Gorlenko and Lebedeva 1971 Chlorobaculum Imhoff 2003 Chlorobium Nadson 1906 emend. Imhoff 2003 Chloroherpeton Gibson et al. 1985 Clathrochloris Witt et al. 1989 Pelodictyon Lauterborn 1913 Prosthecochloris Gorlenko 1970 emend. Imhoff 2003 Class Ignavibacteria Iino et al. 2010 Order Ignavibacteriales Iino et al. 2010 Family Ignavibacteriaceae Iino et al. 2010 Ignavibacterium Iino et al. 2010 Melioribacter roseus ♠ Podosokorskaya et al. 2011

The green sulfur bacteria are a family of obligately anaerobic photoautotrophic bacteria. Most closely related to the distant Bacteroidetes, they are accordingly assigned their own phylum.

Green sulfur bacteria are nonmotile (except Chloroherpeton thalassium, which may glide) and occur in spheres, rods, and spirals. Photosynthesis is achieved using a Type 1 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.

Green sulfur bacteria appear in Lake Matano, Indonesia, at a depth of about 110–120 m. The population may include the species Chlorobium ferrooxidans.

Phylogeny

See also: Bacterial taxonomy

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

Ignavibacteriaceae Ignavibacterium album Iino et al. 2010 Melioribacter roseus ♠ Podosokorskaya et al. 2011 Chlorobiaceae ?Ancalochloris perfilievii ♪ Gorlenko and Lebedeva 1971 ?Clathrochloris sulfurica ♠ Witt et al. 1989 ?Pelodictyon phaeum Gorlenko 1972 Chloroherpeton thalassium Gibson et al. 1985 Prosthecochloris ?P. aphaeoasteroides ♥ ?P. indica ♠ Anil 2005 P. aestuarii Gorlenko 1970 emend. Imhoff 2003 (type sp.) P. vibrioformis (Pelsh 1936) Imhoff 2003 Chlorobium chlorovibrioides ♦ (Gorlenko et al. 1974) Imhoff 2003 Chlorobaculum ?C. limnaeum Imhoff 2003 ?C. macestae ♠ Keppen et al. 2008 ?C. parvum Imhoff 2003 C. tepidum (Wahlund et al. 1996) Imhoff 2003 (type sp.) C. thiosulfatiphilum Imhoff 2003 Chlorobium ?C. bathyomarinum ♠ Beatty et al. 2005 ?C. chlorochromatii ♠ Vogl et al. 2006 (epibiont of the phototrophic consortium Chlorochromatium aggregatum) ?C. gokarna ♠ Anil 2005 ?C. ferrooxidans Heising et al. 1998 emend. Imhoff 2003 C. luteolum (Schmidle 1901) emend. Imhoff 2003 C. phaeovibrioides Pfennig 1968 emend. Imhoff 2003 C. limicola Nadson 1906 emend. Imhoff 2003 (type sp.) C. clathratiforme (Szafer 1911) emend. Imhoff 2003 C. phaeobacteroides Pfennig 1968 emend. Imhoff 2003

Notes:
♪ 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)

See also

• Anoxic event
• Purple sulfur bacteria