Methanobrevibacter smithii
Methanobrevibacter smithii | |
---|---|
Scientific classification | |
Domain: | Archaea |
Kingdom: | Euryarchaeota |
Class: | Methanobacteria |
Order: | Methanobacteriales |
Family: | Methanobacteriaceae |
Genus: | Methanobrevibacter |
Species: | M. smithii
|
Binomial name | |
Methanobrevibacter smithii Balch and Wolfe 1981
|
Methanobrevibacter smithii is the predominant archaeon in the microbiota of the human gut. M. smithii has a coccobacillus shape. 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 a hydrogenotroph that recycles the hydrogen by combining it with carbon dioxide to methane. The removal of hydrogen by M. smithii is thought to allow an increase in the extraction of energy from nutrients by shifting bacterial fermentation to more oxidized end products.[1]
Methanobrevibacter smithii is also found in
Importance in the human gut
The human
The gut microbiota is dominated by
M. smithii has significant enrichment of genes involved in the utilization of
M. smithii supports methanogenic and nonmethanogenic removal of diverse bacterial end products of fermentation.[5]
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.[5] M. smithii, along with certain bacteria, is more often found in lean individuals than in those who are overweight.[6] Researchers have sequenced M. smithii genome, indicating that M. smithii may be a therapeutic target for reducing energy harvest in obese humans.[5]
Cell wall and cell membrane compared to bacteria
The cell wall and cell membrane of Methanobrevibacter smithii determine susceptibility to antibiotics and statins. The cell wall is composed of pseudopeptidoglycan (and not peptidoglycan as in bacteria) which makes archaea resistant to lysozyme and many antibiotics that interfere with cell wall synthesis. The cell membrane consists of a lipid bilayer or monolayer, the backbone of which is composed of isoprene units that are linked to glycerol by ether bonds. In contrast, the lipid bilayer of bacteria consists of a fatty acid backbone that is linked to glycerol by an ester bond. The presence of statin-sensitive isoprene units in the cell membrane of archaea allows statins to selectively interfere with the growth of archaea while leaving the cell membrane of bacteria unaffected. While bacteria do not use isoprene units in their cell membrane they are still required elsewhere. These bacterial isoprene units are, however, synthesized by the mevalonate pathway (MEP) that is not inhibited by statins. [7]
In anorexic patients
In 2009, the largest human study concerning
The development of Methanobrevibacter in anorexia patients may be associated with an adaptive attempt towards optimal exploitation of the low caloric diet of anorexic patients. Hence, an increase in M. smithii leads to the optimization of food transformation in low caloric diets. M. smithii could also be related to constipation, a common condition for anorexic patients.[1]
M. smithii and constipation
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. Statins can inhibit archaeal cell membrane biosynthesis apparently without affecting bacterial numbers as demonstrated in livestock and humans. This opens the possibility of a therapeutic intervention that targets a specific etiological 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, is administered.[7]
References
- ^ PMID 19774074.
- ^ Belay, N; Mukhopadhyay, B; Conway de Macario, E; Galask, R; Daniels, L. 1990. Methanogenic bacteria in human vaginal samples. Journal of Clinical Microbiology, 28 (7), 1666–1668.
- PMID 21317366.
- ^ Bedis, D., Mireille, H. (2009). "High Prevalence of Methanobrevibacter smithii and Methanosphaera stadtmanae Detected in the Human Gut Using an Improved DNA Detection Protocol." PLOS One 4(9) e7063.
- ^ a b c d e Buck, S., Hansen, E., (2007). "Genomic and metabolic adaptations of Methanobrevibacter smithii to the human gut." Proceedings of the National Academy of Sciences of the United States of America 104, 10643-10648.
- PMID 26565087.
- ^ a b Gottlieb, K., Wacher, V., Sliman, J., & Pimentel, M. (2015). Review article: inhibition of methanogenic archaea by statins as a targeted management strategy for constipation and related disorders. Alimentary Pharmacology & Therapeutics.
Further reading
Bang, Corinna; Weidenbach, Katrin; Gutsmann, Thomas; Heine, Holgar; Schmitz, Ruth A. (2014). "The Intestinal Archaea Methanosphaera stadtmanae and Methanobrevibacter smithii Activate Human Dendritic Cells". PLOS ONE. 9 (6): e99411.
Kim, Gene; Deepinder, Fnu; Morales, Walter; Hwang, Laura; Weitsman, Stacy; Chang, Christopher; Gunsalus, Robert; Pimentel, Mark (December 2012). "Methanobrevibacter smithii Is the Predominant Methanogen in Patients with Constipation-Predominant IBS and Methane on Breath". Digestive Diseases and Sciences. 57 (12): 3213–3218.
External links
- Paul B. Eckburg, Paul W. Lepp, and David A. Relman Archaea and Their Potential Role in Human Disease
- Dermoumi, Heide L.; Ansorg, Rainer A.M. (2001). "Isolation and Antimicrobial Susceptibility Testing of Fecal Strains of the Archaeon Methanobrevibacter smithii". Chemotherapy. 47 (3): 177–183. S2CID 29227943.
- Methanogens Photo Gallery—Methanobrevibacter smithii
- LSPN page for Methanobrevibacter
- Samuel BS; Hansen EE; Manchester JK; Coutinho PM; et al. (2007). "Genomic and metabolic adaptations of Methanobrevibacter smithii to the human gut". Proc Natl Acad Sci U S A. 104 (25): 10643–8. PMID 17563350.
- Vianna ME; Conrads G; Gomes BP; Horz HP. (2006). "Identification and Quantification of Archaea Involved in Primary Endodontic Infections". J Clin Microbiol. 44 (4): 1274–82. PMID 16597851.
- Ridlon JM; McGarr SE; Hylemon PB. (2005). "Development of methods for the detection and quantification of 7alpha-dehydroxylating clostridia, Desulfovibrio vulgaris, Methanobrevibacter smithii, and Lactobacillus plantarum in human feces". Clin Chim Acta. 357 (1): 55–64. PMID 15963794.
- Type strain of Methanobrevibacter smithii at BacDive - the Bacterial Diversity Metadatabase
- Methanobrevibacter - What we know about the most abundant archaea in the human gut