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Methanobrevibacter smithiiRANK: SpeciesTAXONOMY: Archaea -> Euryarchaeota -> Methanobacteria -> Methanobacteriales -> Methanobacteriaceae -> Methanobrevibacter -> Methanobrevibacter smithii OVERVIEW: '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. M. smithii (coefficient=-0.43, 95% CI -0.90 to 0.05; P=0.08) was negatively associated with the BMI. [PMID: 23459324 ] Is negatively correlated with BMI. Increased in anorexic patients. Observational studies show a strong association between delayed intestinal transit and the production of methane. Experimental data suggest a direct inhibitory activity of methane on the colonic and ileal smooth muscle and a possible role for methane as a gasotransmitter. Archaea are the only confirmed biological sources of methane in nature and Methanobrevibacter smithii is the predominant methanogen in the human intestine. [PMID: 26559904] Statins can inhibit archaeal cell membrane biosynthesis without affecting bacterial numbers as demonstrated in livestock and humans. This opens the possibility of a therapeutic intervention that targets a specific aetiological factor of constipation while protecting the intestinal microbiome. While it is generally believed that statins inhibit methane production via their effect on cell membrane biosynthesis, mediated by inhibition of the HMG-CoA reductase, there is accumulating evidence for an alternative or additional mechanism of action where statins inhibit methanogenesis directly. It appears that this other mechanism may predominate when the lactone form of statins, particularly lovastatin lactone, is administered. [PMID: 26559904] This species has been identified as a resident in the human gastrointestinal tract based on the phylogenetic framework of its small subunit ribosomal RNA gene sequences.[PMC 4262072]
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