Methanothermobacter thermautotrophicus

A Microbial Biorealm page on the genus Methanothermobacter thermautotrophicus

Classification

Higher order taxa

Cellular organisms; Archaea; Euryarchaeota; Methanobacteria;Methanobacteriales; Methanobacteriaceae; Methanothermobacter

Species

NCBI: Taxonomy

Genus: Methanothermobacter

Species: Thermautotrophicus

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 anaerobic (does not need oxygen), nonmotile (not capable of movement on the microorganism level, methane (CH3) producing archeon. The growth of this organism occurs between the pH of around 7. This strain can be found in thermophilic, anaerobic areas such as sewage slude 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.

http://www.ncbi.nlm.nih.gov/sutils/static/GP_IMAGE/Diversity.jpg

Genome structure

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 bacteria 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-sepcfic cell walls called pseudomurein which is similar to how peptidoglycan of eubacteria work. Methanothermobacter thermautotrophicus is thermophillic with an optimal growth temperature of 65-70 degrees Celsius.

Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence? Does it have any plasmids? Are they important to the organism's lifestyle?

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 subtrates 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)

Describe any interesting features and/or cell structures; how it gains energy; what important molecules it produces.

Ecology

Methanothermobacter thermautotrophicus is a methanogen which produces methane.

Pathology

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)

Current Research

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.

First such experiments is the understanding of the diversity of AMP-forming acetyl-CoA synthetases in Archaea which utilize a wide range of substrates. By comparing two enzymes, revealed that ACS from Methanothermobacter thermautotrophicus (designated as MT-ACS1) and an ACS from Archaeoglobus fulgidus (designated as AF-ACS2), revealed that these enzymes 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 was isolated. The result was “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)