Methanobacterium thermoautotrophicum
Bianca McCollough

IDENTIFYING CHARACTERISTICS 0.2 - 1.0 mm x 1.2 - 120 mm in size.

  1. Optimum temperature ranges from 35 - 70oC (moderate thermophile with a optimum growth temperature of 65OC).
  2. Optimum pH ranges from 6.0 - 8.5.
  3. Strictly anaerobic.
  4. Straight or slightly curved rods, but not helical.
  5. Cells stain Gram negative.
  6. Nonmotile.
  7. Endospores are not present.
  8. Cell envelope compostion is mostly pseudomurein.
  9. Chemoautotrophs.
  10. Requires only CO2, H2 and salts for growth.
  11. All use ammonium, sulfide, and elemental sulfur.
  12. Habitat contains low NaCl concentrations.
  13. Positioned near the `center' of the methanogen evolutionary tree.

TAXONOMIC DESCRIPTION

The species within the genus Methanobacterium vary widely in length and filaments are common. Cell walls appear to be Gram positive, but are composed of pseudomurein rather than peptidoglycan. They are non-motile and flagella are absent. Metabolism is strictly anaerobic and H2 and/or formate are used as an electron donor. All species grow with H2 and CO2 as a substrate for methanogenesis. Cells are mesophillic or thermophillic. All species fail to grow under aerobic conditions and most are acid tolerant (will grow at pH less than 5). There are 12 species of genus Methanobacterium and they have been isolated from aneraobic digestors, sewage sludge, manure, groundwater, and formation water of oil-bearing rocks.

ISOLATION AND ECOLOGY

There are several media available for the isolation of methanobacteria. Most of the media consist of yeast extract in combination with compounds such as xylose, tryptone, and glucose. Also, antibiotics in conjunction with enrichment techniques can be useful as selective agents in isolating methanobacteria. However, methanobacteria must be present in the soil in order for successful isolation to occur.

APPLICATIONS OF METHANOGENS

Methane, also known as natural gas or biogas, is generated in the final step of the anaerobic biodegradation of industrial, urban and agricultural waste materials and, as such, represents a major, renewable energy source. However, methane is also a greenhouse gas and methane production contributes substantially to global warming.

USES OF METHANOGENS IN BIOREMEDIATION

Biodegredation is used by all industrialized and non-industrialized countries to reduce and detoxify municipal, commercial and agricultural wastes, in industrial and municipal sewage treatment facilities, in septic tanks and in landfills. The process works empirically, but opportunities may well exist to improve and control this biotechnology, to convert more waste to methane and to decrease methane contributions to global warming.

*Disclaimer - This report was written by a student participaring in a microbiology course at the Missouri University of Science and Technology. The accuracy of the contents of this report is not guaranteed and it is recommended that you seek additional sources of information to verify the contents.

 

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