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''Methanosarcina acetivorans'' is a versatile methane producing microbe which is found in such diverse environments as oil wells, trash dumps, deep-sea hydrothermal vents, and oxygen-depleted sediments beneath kelp beds. Only ''M. acetivorans'' and microbes in the genus ''Methanosarcina'' use all three known metabolic pathways for methanogenesis.〔()〕 Methanosarcinides, including ''M. acetivorans'', are also the only archaea capable of forming multicellular colonies, and even show cellular differentiation. , the genome of ''M. acetivorans'' is the largest of all sequenced archaeal genomes.〔http://microbewiki.kenyon.edu/index.php/Methanosarcina〕 In 2006, James Ferry and Christopher House discovered that ''M. acetivorans'' uses a previously unknown metabolic pathway to metabolize carbon monoxide into methane and acetate using the well known enzymes phosphotransacetylase (PTS) and acetate kinase (ACK). This pathway is surprisingly simple, and has been proposed by Ferry and House as perhaps the first metabolic pathway used by primordial microbes. However, in the presence of minerals containing iron sulfides, as might have been found in sediments in a primordial environment, acetate would be catalytically converted into acetate thioester, a sulfur-containing derivative. Primitive microbes could obtain biochemical energy in the form of adenosine triphosphate (ATP) by converting acetate thioester back into acetate using PTS and ACK, which would then be converted back into acetate thioester to complete the process. In such an environment, a primitive "protocell" could easily produce energy through this metabolic pathway, excreting acetate as waste. Furthermore, ACK catalyzes the synthesis of ATP directly. Other pathways generate energy from ATP only through complex multi-enzyme reactions involving protein pumps and osmotic imbalances across a membrane. ==See also== * RNA world * Origin of life 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「Methanosarcina acetivorans」の詳細全文を読む スポンサード リンク
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