Methanogens are autotrophic procaryotes that belong to the Archaeobacteria kingdom. These microorganisms produce methane as a byproduct of its metabolism ie. the decomposition of organic materials.
Classification There are 3 groups of Archaeobacteria; this include halophiles, thermophiles and methanogens.   The Archaeobacteria kingdom can then be divided into Archaea and Bacteria where Methanogens falls under the Archaea group. Under the Archaea group, it can be divided again into the phylums Euryarchaeota and Crenarchaeota and the methanogens being under Euryarchaeota.Methanogens are therefore classified as the eurya-archareota of the archaea group of the Archaeobacteria kingdom.
Description Methanogens are usually coccoid (spherical) or bacilli (rod shaped) in shape. Some examples of rod shaped cells include Methanobacterium spp. and Methanopyrus kandleri.   Examples of the coccoid methanogens include species from Methanococcus and Methanosphaera.
Where are they found Methanogens are found in extreme environments with anaerobic conditions that is without oxygen.   This includes sediments at the bottom of lakes and ponds, the intestinal tracts of animals,   sewage lagoons, bogs, swamps, wetlands, oil-contaminated groundwater at underground oil storage facilities, hydrothermal vents etc.
Methanogens can be divided into 5 categories, they are thermophilic, psychrophily, halophilic and acidophilic and alkaliphilic. Methanogens can be thermophilic that is heat loving such as in volcanic hot springs and sofataras where temperatures range from 40 to 100 degrees Celsius and in undersea hydrothermal vents where temperatures can be as high as 350 degrees Celsius because of the pressure. Methanogens can be Psychrophily that is cold loving but this is rare. Methanogens can be halophilic that is salt loving such as salt marshes.   Methanogens can be acidophilic that is acid loving but it’s rare for them to live where the pH levels are less than 4 such as peat bogs. This is...