A Microbial Biorealm page on the genus Methanothermobacter thermautotrophicus
Higher order taxa
Cellular organisms; Archaea; Euryarchaeota; Methanobacteria; Methanobacteriales; Methanobacteriaceae; Methanothermobacter
Description and significance
Methanothermobacter thermautotrophicus is a methanogenic, Gram-positive microorganism consisting of pseudomurein (3). Pseudomurein is also known as peptidoglycan which is a major component of the cell wall of some archaebacteria that is only chemically different but structurally and morphologically the same as bacteria peptidoglycan. A certain strain of Methanothermobacter thermautotrophicus called Methanothermobacter thermautotrophicus str. Delta H which the genome was completely sequenced by Oscient Pharmaceuticals Corporation/Ohio State University, is an anaerobic (does not need oxygen), nonmotile (not capable of movement on the microorganism level), methane (CH3) producing archeon. The growth of this organism occurs at a pH of around 7. This strain can be found in thermophilic, anaerobic areas such as sewage sludge digestors and was discovered and isolated from sewage sludge in 1971 in Urbana, Illinois. (7)
Methanothermobacter thermautotrophicus is used in research purposes in order to better understand the evolution of archeabacteria. It is assumed that archeabacteria and bacteria evolved in parallel. For example, a protein with nuclease-ATPase activity, Nar71 was isolated from Methanothermobacter thermautotrophicus cell extracts as part of an archaeal DNA-repair system.(9) Another finding was the use of the horizontal gene transfer which was evidence of divergence that occurred and which help better understand the ancestry of Methanothermobacter thermautotrophicus to other lineages.
The 1,751,377-bp sequence of the archeaon, Methanobacter thermautotrophicus str. Delta H, has been completely sequenced by Genome Therapeutics Corporation through the process of gene shotgun sequencing. This strain is the only currently mapped out genome of the species. It contains 1921 genes and has a length of 1,751,377 nt. Also, this strain contains 48 structural RNAs and the chromosome consists of a circular topology. (7)
Methanothermobacter thermautotrophicus grows and gains energy through the conversion of hydrogen and carbon dioxide to methane. It was discovered that Methanothermobacter thermoautotrophicus has archaea-specific cell walls called pseudomurein which is similar to how peptidoglycan of eubacteria work. Methanothermobacter thermautotrophicus is thermophilic with an optimal growth temperature of 65-70 degrees Celsius.
Cell structure and metabolism
A closely related species to M. thermautotrophicus is M. thermautotrophicum which has an interesting feature. This archaeabacteria has the ability to produce energy productively by using H2 to reduce carbon dioxide molecules into methane and synthesizes all of its cellular components from gaseous substrates including N2 or NH4, and other inorganic salts. Through this way, M. thermoautotrophicum produces its energy and thus is a very energy efficient archaeabacteria. (7)
Through the use of M. thermautotrophicus cell-free homogenates, the production of archaeal ether-type glycolipids was researched. Glycolipids provide energy and serve as markers for cellular recognition. It is a crucial part to the archaeabacteria M. thermautotrophicus in biosynthesis. (4)
Methanothermobacter thermautotrophicus is a methanogen which produces methane.
There are no pathologies.
Application to Biotechnology
The methanogenic potential in a high temperature natural gas fields in Japan produce biogenic methane. Biogenic methane (produced by methanogens such as M. thermautotrophicus) and thermogenic methane (produced by thermochemical degradation of organic matter) are almost indistinguishable in their characteristics as methane. Recent experiments were done in Japan to better understand the production of biogenic methane. Through the use of 16s rRNA gene libraries and culture-based methods water samples were made to better understand the production of biogenic methane. Although the great majority of methane deposits are thermogenic, the ability to manipulate biogenic methane will help produce oil organically. (10)
There have been many experiments to better understand methanogens which produce high amounts of methane. The study of specific pathways which Methanothermobacter thermautotrophicus produces certain products and byproducts will help better understand the exact processes in which they work.
One such experiment is the understanding of the diversity of AMP-forming acetyl-CoA synthetases (ACS)in Archaea which utilize a wide range of substrates. Comparing two enzymes revealed that ACS from Methanothermobacter thermautotrophicus (designated as MT-ACS1) and an ACS from Archaeoglobus fulgidus (designated as AF-ACS2), have very different properties. (11)
Second research covered mutational analyses of the trpY archaeal transcription regulator. The experiment showed that more than “90 percent of Methanothermobacter thermautotrophicus mutants isolated as spontaneously resistant to 5-methyl tryptophan (5MT) had mutations in trpY gene.” The results of further testing revealed that “DNA binding was sufficient for TrpY repression of trpY transcription.” (5)
Third article covered the “spontaneous mutant of Methanothermobacter thermautotrophicus resistant to the Na+/H+ antiporter inhibitor amiloride was isolated.” Amiloride works by blocking sodium channels. The electrochemical gradients, specifically Na+ and H+ of Methanothermobacter thermautotrophicus were examined to better understand the spontaneous mutation resistant to the Na+/H+ antiporter inhibitor amiloride . The result was that “methanogenesis rates in the mutant strain were higher than wild-type cells and resistant to the inhibitory effect of 2 mM amiloride. Also, ATP synthesis driven by methanogenic electron transport or by an electrogenic potassium efflux in the presence of sodium ions was significantly enhanced in the mutant cells.” (6)
(2) Nucleic Acids Res. 2006;34(20):5829-38. "Structural basis of the Methanothermobacter thermautotrophicus MCM helicase activity PubMed" Epub 2006 Oct 24. Costa A, Pape T, van Heel M, Brick P, Patwardhan A, Onesti S.
(3)Mol Microbiol. 2006 Dec;62(6):1618-30 "Identification of pseudomurein cell wall binding domains" Steenbakkers PJ, Geerts WJ, Ayman-Oz NA, Keltjens JT Department of Microbiology, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, the Netherlands PubMed
(6)FEMS Microbiol Lett. 2007 Apr;269(2):301-8. Epub 2007 Feb 5 "Isolation and characterization of an amiloride-resistant mutant of Methanothermobacter thermautotrophicus possessing a defective Na+/H+ antiport." Surin S, Cubonova L, Majernik AI, McDermott P, Chong JP, Smigan P PubMed
(10)“Microbial diversity and methanogenic potential in a high temperature natural gas field in Japan” Mochimaru H, Yoshioka H, Tamaki H, Nakamura K, Kaneko N, Sakata S, Imachi H, Sekiguchi Y, Uchiyama H, Kamagata Y.
Edited by Anthony Kim, student of Rachel Larsen and Kit Pogliano