Methanogens Methanogens are microorganisms that produce methane as a metabolic byproduct in hypoxic conditions. They are prokaryotic and belong to the domain Archaea. All known methanogens are members of the archaeal phylum Euryarchaeota. Methanogens are comm ...

are a group of

microorganisms A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...

that produce

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...

as a byproduct of their metabolism. They play an important role in the digestive system of

ruminants Ruminants ( suborder Ruminantia) are hoofed herbivorous grazing or browsing mammals that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through microbial actions. The ...

. The

digestive tract The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans a ...

of ruminants contains four major parts:

rumen The rumen, also known as a paunch, is the largest stomach compartment in ruminants and the larger part of the reticulorumen, which is the first chamber in the alimentary canal of ruminant animals. The rumen's microbial favoring environment allow ...

reticulum Reticulum is a small, faint constellation in the southern sky. Its name is Latin for a small net, or reticle—a net of crosshairs at the focus of a telescope eyepiece that is used to measure star positions. The constellation is best viewed b ...

omasum The omasum, also known as the bible, the fardel, the manyplies and the psalterium, is the third compartment of the stomach in ruminants. The omasum comes after the rumen and reticulum and before the abomasum. Different ruminants have different oma ...

and

abomasum The abomasum, also known as the maw,The Cham ...

. The food with saliva first passes to the rumen for breaking into smaller particles and then moves to the reticulum, where the food is broken into further smaller particles. Any indigestible particles are sent back to the rumen for rechewing. The majority of anaerobic microbes assisting the cellulose breakdown occupy the rumen and initiate the fermentation process. The animal absorbs the fatty acids, vitamins and nutrient content on passing the partially digested food from the rumen to the omasum. This decreases the pH level and initiates the release of enzymes for further breakdown of the food which later passes to the abomasum to absorb remaining nutrients before excretion. This process takes about 9–12 hours. Some of the microbes in the ruminant digestive system are: *'' Fibrobacter (Bacteroides) succinogenes'' is a

gram negative The gram (originally gramme; SI unit symbol g) is a unit of mass in the International System of Units (SI) equal to one one thousandth of a kilogram. Originally defined as of 1795 as "the absolute weight of a volume of pure water equal to th ...

, cellulolytic and

amylolytic An amylase () is an enzyme that catalyses the hydrolysis of starch (Latin ') into sugars. Amylase is present in the saliva of humans and some other mammals, where it begins the chemical process of digestion. Foods that contain large amounts of ...

methanogen that produces formates, acetates and succinates. *'' Ruminococcus albus'' is a cellulolytic, xylanolytic bacterium producing ethanol, hydrogen, carbon dioxide, formates and acetates. *'' Ruminococcus flavefaciens'' is a cellulolytic, xylanolytic bacteria producing formates, acetates, hydrogen and succinates. *''

Butyrivibrio fibrisolvens ''Butyrivibrio'' is a genus of bacteria in Class Clostridia. Bacteria of this genus are common in the gastrointestinal systems of many animals. Genus ''Butyrivibrio'' was first described by Bryant and Small (1956) as anaerobic, butyric acid-pr ...

'' is a

proteolytic Proteolysis is the breakdown of proteins into smaller polypeptides or amino acids. Uncatalysed, the hydrolysis of peptide bonds is extremely slow, taking hundreds of years. Proteolysis is typically catalysed by cellular enzymes called proteases, ...

, cellulolytic, xylanolytic microbe producing lactate, butyrate, ethanol, hydrogen, carbon dioxide, formates and acetates. *''

Streptococcus bovis ''Streptococcus bovis'' (''S. bovis'') is a species of Gram-positive bacteria that in humans is associated with urinary tract infections, endocarditis, sepsis, Ryan K.J. and C.G. Ray CG (editors). 2004. ''Sherris Medical Microbiology'' (4th ed.). ...

'' is an amylolytic, major soluble sugar

ferment Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food ...

er, proteolytic, microbe resulting in lactate, acetate and formate. *'' Ruminobacter (Bacteroides) amylophilus'' amylolytic,

propionate Propionic acid (, from the Greek words πρῶτος : ''prōtos'', meaning "first", and πίων : ''píōn'', meaning "fat"; also known as propanoic acid) is a naturally occurring carboxylic acid with chemical formula CH3CH2CO2H. It is a liqu ...

, proteolytic, organism that forms,

formate Formate (IUPAC name: methanoate) is the conjugate base of formic acid. Formate is an anion () or its derivatives such as ester of formic acid. The salts and esters are generally colorless.Werner Reutemann and Heinz Kieczka "Formic Acid" in ''Ull ...

s, acetates and succinates. *'' Prevotella (Bacteroides) ruminocola'' amylolytic, xylanolytic, propionate, proteolytic, microbe that creates, formates, acetates, succinates and propionate. *'' Succinimonas amylolytica'' amylolytic, dextrinolytic, bacteria forming

acetate An acetate is a salt (chemistry), salt formed by the combination of acetic acid with a base (e.g. Alkali metal, alkaline, Alkaline earth metal, earthy, Transition metal, metallic, nonmetallic or radical Radical (chemistry), base). "Acetate" als ...

s and

succinate Succinic acid () is a dicarboxylic acid with the chemical formula (CH2)2(CO2H)2. The name derives from Latin ''succinum'', meaning amber. In living organisms, succinic acid takes the form of an anion, succinate, which has multiple biological ro ...

s. *''

Selenomonas ruminantium ''Selenomonas ruminantium'' is a species of ''Selenomonas'' bacteria which are closely associated with ruminants, aiding in digestion of their food. It is predominantly observed in the rumen of these animals, and is strictly anaerobic. Shape a ...

'' amylolytic, major soluble sugar fermenter, glycerol-utilizing, lactate-utilizing, proteolytic, microbe producing acetates, lactates, hydrogen, carbon dioxide and propionates. *'' Lachnospira multiparus'' propionate, proteolytic, A microbe that results in production of lactate, ethanol, hydrogen, carbon dioxide, formates and acetates. *'' Succinivibrio dextrinosolvens'' propionate, dextrinolytic, bacteria forming formates, acetates, lactates and succinates *''

Methanobrevibacter ruminantium In alpha taxonomy, taxonomy, ''Methanobrevibacter'' is a genus (biology), genus of the Methanobacteriaceae.See the National Center for Biotechnology Information, NCBI]webpage on Methanobrevibacter Data extracted from the The species within ''Me ...

'' methanoic, hydrogen utilizing, archaea involved in the creation of methane *''

Methanosarcina barkeri '' Methanosarcina barkeri'' is the most fundamental species of the genus '' Methanosarcina'', and their properties apply generally to the genus ''Methanosarcina''. ''Methanosarcina barkeri'' can produce methane anaerobically through different m ...

'' methanoic, hydrogen utilizing, archaea involved in the creation of methane and carbon dioxide.

References

{{Reflist Ruminants Microorganisms Digestive system Methane