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''Methanobrevibacter smithii'' is the predominant archaeon in the human gut. It plays an important role in the efficient digestion of polysaccharides (complex sugars) by consuming the end products of bacterial fermentation. ''Methanobrevibacter smithii'' is a single-celled microorganism from the Archaea domain. ''M. smithii'' is a methanogen, and recycles the hydrogen in methane, allowing for an increase in the extraction of energy from nutrients. ==Importance in the human gut== The human gut flora consist of three main groups of hydrogen consuming microbes: methanogens including ''M. smithii''; a polyphyletic group of acetogenic bacteria; and sulfate-reducing bacteria. Defining the roles of these microbes is significant in the understanding of how hydrogen metabolism affects the efficiency of fermentation of dietary components. Accumulation of hydrogen in the gut reduces the efficiency of microbial fermentation as well as the yield of energy. Methanogenic archaea are therefore particularly significant for the human gut, because they are pivotal in the removal of excess hydrogen.〔 ''M. smithii'' is the most common methanogenic archaeon in the human gut microbiota. Although ''M. smithii'' is paramount in digestive processes, it has a low prevalence in human feces.〔Bedis, D., Mireille, H. (2009). "High Prevalence of ''Methanobrevibacter smithii'' and ''Methanosphaera stadtmanae'' Detected in the Human Gut Using an Improved DNA Detection Protocol."〕 The human gut microbiota is dominated by Bacteroidetes and Firmicutes. Archaea are most prominently represented by the methanogenic ''M. smithii''. ''M. smithii'' is believed to be a therapeutic target for manipulation and an adaptation to the gut ecosystem.〔Buck, S., Hansen, E., (2007). "Genomic and metabolic adaptations of ''Methanobrevibacter smithii'' to the human gut." 104, 10643-10648.〕 ''M. smithii'' has significant enrichment of genes involved in the utilization of CO2, H2, and formate for methanogenesis. It also has an intact pathway to allow for CO2 utilization gene cluster for the methanogenic consumption of ''B. thetaiotaomicron''-produced metabolite.〔 ''M. smithii'' supports methanogenic and nonmethanogenic removal of diverse bacterial end products of fermentation.〔 The dominant archaeon in the human gut ecosystem affects the specificity and efficiency of bacterial digestion of dietary polysaccharides. This influences the person’s calorie harvest and body fat. Researchers have sequenced ''M. smithii'' genome, indicating that ''M. smithii'' may be a therapeutic target for reducing energy harvest in obese humans. 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「Methanobrevibacter smithii」の詳細全文を読む スポンサード リンク
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