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Phototrophy is the process by which organisms trap light energy (photons) and store it as chemical energy in the form of ATP and/or reducing power in NADPH. There are two major types of phototrophy: chlorophyll-based chlorophototrophy and rhodopsin-based retinalophototrophy. Chlorophototrophy can further be divided into oxygenic photosynthesis and anoxygenic phototrophy. Oxygenic and anoxygenic photosynthesizing organisms undergo different reactions either in the presence of light or with no direct contribution of light to the chemical reaction (colloquially called "light reactions" and "dark reactions", respectively). ==Overview== Anoxygenic photosynthesis is the phototrophic process where light energy is captured and converted to ATP, without the production of oxygen. Water is therefore not used as an electron donor. There are several groups of bacteria that undergo anoxygenic photosynthesis: Green sulfur bacteria, green and red filamentous anoxygenic phototrophs (FAPs), phototrophic purple bacteria, phototrophic Acidobacteria, and phototrophic heliobacteria.〔(A. Bryant, Niels-Ulrik Frigaard, Prokaryotic photosynthesis and phototrophy illuminated, Trends in Microbiology, Volume 14, Issue 11, November 2006, Pages 488-496, ISSN 0966-842X, 10.1016/j.tim.2006.09.001. (http://www.sciencedirect.com/science/article/pii/S0966842X06002265) )〕〔Candidatus Chloracidobacterium thermophilum: An Aerobic Phototrophic Acidobacterium Donald A. Bryant, Amaya M. Garcia Costas, Julia A. Maresca, Aline Gomez Maqueo Chew, Christian G. Klatt, Mary M. Bateson, Luke J. Tallon, Jessica Hostetler, William C. Nelson, John F. Heidelberg, and David M. Ward Science 27 July 2007: 317 (5837), 523-526. 〕 Anoxygenic phototrophs have photosynthetic pigments called bacteriochlorophylls (similar to chlorophyll found in eukaryotes). Bacteriochlorophyll ''a'' and ''b'' have wavelengths of maximum absorption at 775 nm and 790 nm, respectively in ether. ''In vivo'' however, due to shared extended resonance structures, these pigments were found to maximally absorb wavelengths out further into the near-infrared. Bacteriochlorophylls ''c-g'' have the corresponding "peak" absorbance at more blue wavelengths when dissolved in an organic solvent, but are similarly red-shifted within their natural environment (with the exception of bacteriochlorophyll ''f'', which has not been naturally observed). Unlike oxygenic phototrophs, anoxygenic photosynthesis only functions using (by phylum) either one of two possible types of photosystem. Anyoxygenic photosynthesis uses molecules such as H2S as opposed to H2O. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「anoxygenic photosynthesis」の詳細全文を読む スポンサード リンク
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