Archaebacteria

hiMethanogens Methanogens (methanobacterium thermoautotrophicum) are Archaebacteria in the Genus Methanobacterium. They are in Phylum Euryarchaeota because their RNA sequences differ from other archaeans. There are around 50 types of methanogens and some are even extremophiles, meaning that they live under extreme conditions. __** Introduction **__ Methanogens are microorganisms that naturally create methane as a side product of its metabolism. They are obligate anaerobes, meaning that they cannot live in the presence of oxygen, thus they are found in intestines of animals and humans and in wetlands where oxygen levels are low. Methanogens produce methane gas by using a source of carbon and a source of energy. There are many different methanogens that use many different combinations of both. Two common types of methanogens are the hydrotrophic methanogens and the acetotrophic methanogens. The hydrotrophic methanogens use carbon dioxide gas as a source of carbon and hydrogen gas as a source of energy. As the methanogen goes through its metabolism, the carbon dioxide gas (CO2) and the hydrogen gas (H2) react and a byproduct of CH4 (methane gas) is formed. Acetotrophic methanogens use acetate (CH3COO-) as both a source of energy and carbon. They and create methane in the same manner as hydrotrophic methanogens do; while going through its metabolism.

__** Features **__ The cells of methanogens usually have two shapes; rod-shaped (bacilli) and cocci. There are also methanogens with aplate-like structure. Methanogens have unique enzymes and cofacters, and have the typical archaebacteria cell structure, meaning that they do not have nuclei in their cells nor do they have membrane-bound organelles. Their DNA are also single-stranded and circular.  The cells can be both gram-positive-meaning able to have a stain or coloring, or gram-negative-meaning that they are unable to keep a stain in their membrane and appear as transparent cells. The approximate size of a methanogen cell is 2 um (micrometers).

**__ Functions __** Methanogens produce methane as a byproduct, therefore it is responsible for many things in life. For example, methanogens in the large intestines of humans and animals are responsible for flatulence (passing gas). The methanogens in sewage systems act as decomposers, which help us a lot in keeping the Earth healthy. In swamps and other wetlands, methanogens generate methane in the form of marsh gas. This gas can be used by us humans to heat our homes and provide energy for gas-fueled lamps.

**__ Interesting Facts __**



The soil and vapour on Mars have signs of methanogen in them. This might give us a clue that there is life on mars.



Marsh gas, produced by methanogens in wetlands, is lighter than air and floats in an eerie cloud. If it is burned, it releases a mysterious blueish-purple flame. This might explain some sightings of UFOs and unexplained mysterious lights that appear in swampy areas. It might also be responsible for numerous ghost stories.

__Sources__For Introduction and Functions:http://www.daviddarling.info/encyclopedia/M/methanogen.html, __The Internet Encyclopedia of Science__, "methanogens"http://www.link.vet.ed.ac.uk/clive/cal/rumencal/info/infmeth.html, "Methanogens"For Features and Functions:http://microbewiki.kenyon.edu/index.php/Methanogens, __Microbe Wiki__, "Methanogens" For Interesting Facts:http://ask.yahoo.com/20000127.html, __Ask Yahoo!__, "What is marsh gas"http://www.sciencedaily.com/releases/2007/05/070525204839.htm, __Science Daily__, "Model Methanogens Provide Clues To Possible Mars Life"