Methanogens

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 because the ideal pH level for methanogenesis to occur is at 6. Methanogenesis is the process of degrading hydrocarbons with the end product being methane (CH4) gas and carbon dioxide. Methanogens can be alkaliphilic that is base or alkali loving. They are found to live in pH levels above 8. Role in the ecosystem The role that methanogens play in the ecosystem is to use hydrogen or hydrogen rich compounds and carbon dioxide to produce energy for themselves and release methane gas (CH4) as a waste product into the atmosphere. As Methanogens live in anaerobic environments where there are hydrogen gas and carbon dioxide, they take 5% of CO2 and reduce it to cell material while the other 95% are reduced to methane. Importance in the ecosystem Methanogens play an important role in the carbon cycle by producing methane. This is because methanogenesis removes the final products of decay, they are hydrogen, some small organic material and carbon dioxide. Without methanogens and methanogenesis, excessive amounts of carbon would accumulate in anaerobic environments. Methanogens helps removes carbon dioxide from the environment and converting CO2 into cell material and being released as methane. Evidence for evolution In the past, Methanogens were more widespread as early Earth was more anaerobic. Oxygen was rare and toxic to the inhabitants of early Earth. Oxygen was not needed to be inhaled by them. However when cyanobacteria inhabited Earth in the Precambrium period, they produced oxygen as a waste gas which helped establish an aerobic ecosystem and as a result there was a decrease in anaerobic environments. The presence of Archaebacteria has changed Earth dramatically. They helped establish a stable atmosphere, and produced oxygen in quantities that eventually life forms could evolve that needed oxygen in stead of producing it. The new atmospheric conditions calmed the weather so that the extremes were less severe. These prokaryotes have allowed complex life to form. Despite the decrease in anaerobic and extreme environments, Methanogens today can still be found in anaerobic conditions in the environments listed earlier.