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'' Methanosarcina barkeri'' is the most fundamental species of the genus ''
Methanosarcina ''Methanosarcina'' is a genus of euryarchaeote archaea that produce methane. These single-celled organisms are known as anaerobic methanogens that produce methane using all three metabolic pathways for methanogenesis. They live in diverse envi ...
'', and their properties apply generally to the genus ''Methanosarcina''. ''Methanosarcina barkeri'' can produce methane anaerobically through different
metabolic pathway In biochemistry, a metabolic pathway is a linked series of chemical reactions occurring within a cell. The reactants, products, and intermediates of an enzymatic reaction are known as metabolites, which are modified by a sequence of chemical reac ...
s. ''M. barkeri'' can subsume a variety of molecules for ATP production, including
methanol Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is a ...
,
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 ...
,
methylamine Methylamine is an organic compound with a formula of . This colorless gas is a derivative of ammonia, but with one hydrogen atom being replaced by a methyl group. It is the simplest primary amine. Methylamine is sold as a solution in methanol, ...
s, and different forms of hydrogen and carbon dioxide. Although it is a slow developer and is sensitive to change in environmental conditions, ''M. barkeri'' is able to grow in a variety of different substrates, adding to its appeal for
genetic analysis Genetic analysis is the overall process of studying and researching in fields of science that involve genetics and molecular biology. There are a number of applications that are developed from this research, and these are also considered parts of ...
. Additionally, ''M. barkeri'' is the first organism in which the amino acid
pyrrolysine Pyrrolysine (symbol Pyl or O; encoded by the 'amber' stop codon UAG) is an α-amino acid that is used in the biosynthesis of proteins in some methanogenic archaea and bacteria; it is not present in humans. It contains an α-amino group (which is ...
was found. Furthermore, two strains of ''M. barkeri'', ''M. b. Fusaro'' and ''M. b. MS'' have been identified to possess an F-type
ATPase ATPases (, Adenosine 5'-TriPhosphatase, adenylpyrophosphatase, ATP monophosphatase, triphosphatase, SV40 T-antigen, ATP hydrolase, complex V (mitochondrial electron transport), (Ca2+ + Mg2+)-ATPase, HCO3−-ATPase, adenosine triphosphatase) are ...
(unusual for archaea, but common for bacteria,
mitochondria A mitochondrion (; ) is an organelle found in the Cell (biology), cells of most Eukaryotes, such as animals, plants and Fungus, fungi. Mitochondria have a double lipid bilayer, membrane structure and use aerobic respiration to generate adenosi ...
and
chloroplasts A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, ...
) along with an A-type ATPase.


Location and structure

The fusaro strain of ''M. barkeri'' was found in mud samples taken from Lake Fusaro, a freshwater lake near Naples. ''M. barkeri'' also lives in the
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 ...
of cattle, where it works in tandem with other microbes to digest polymers. ''Methanosarcina barkeri'' can also be found in sewage, landfills, and in other freshwater systems.
Morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines * Morphology (archaeology), study of the shapes or forms of artifacts * Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...
of ''Methanosarcina'' cells depends on growing conditions, e.g. on salt concentrations. ''M. barkeri'' shows this variable morphology: when grown in freshwater medium, these microbes grow into large, multicellular aggregates embedded in a matrix of methanochondroitin, while growing in marine environment as single, irregular cocci, only surrounded by the
S-layer An S-layer (surface layer) is a part of the cell envelope found in almost all archaea, as well as in many types of bacteria. The S-layers of both archaea and bacteria consists of a monomolecular layer composed of only one (or, in a few cases, two) i ...
, but no methanochondroitin. The aggregates can grow large enough to be seen by the naked eye. ''Methanosarcina'' could produce positive
Gram The gram (originally gramme; SI unit symbol g) is a Physical unit, 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 wate ...
stain, but generally, it is Gram variable. ''M. barkeri'' has a thick cell wall compounded by a short lipid cell membrane that is similar in structure to most other
methanogen 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 com ...
s. However, its cell walls do not contain
peptidoglycan Peptidoglycan or murein is a unique large macromolecule, a polysaccharide, consisting of sugars and amino acids that forms a mesh-like peptidoglycan layer outside the plasma membrane, the rigid cell wall (murein sacculus) characteristic of most ...
. ''M. barkeri'' str. ''fusaro'' has no flagellum but has potential for movement through the creation of gas
vesicle Vesicle may refer to: ; In cellular biology or chemistry * Vesicle (biology and chemistry), a supramolecular assembly of lipid molecules, like a cell membrane * Synaptic vesicle ; In human embryology * Vesicle (embryology), bulge-like features o ...
s. These gas vesicles have only been produced in the presence of hydrogen and carbon dioxide, likely acting as a response to a hydrogen gradient. ''M. barkeri''s chromosome is large and circular, derived from its remarkable ability to metabolize a variety of different carbon molecules. This offers the species an advantage as though it is immotile, it can adapt to its environment depending on the energy sources available. ''M. barkeri''s circular plasmid consists of about twenty genes.


Applications and importance

''Methanosarcina barkeri''s unique nature as an anaerobic methanogen that ferments many carbon sources can have many implications for future biotechnology and environmental studies. As ''M. barkeri'' is found in the rumen of cows, a place with an extreme dearth of oxygen, it is classified as an extreme anaerobe. Furthermore, the methane gas produced by cows due to ''M. barkeri'' could play a role in greenhouse gas production. However, since ''M. barkeri'' can survive in extreme conditions and produce methane, ''M. barkeri'' can be implemented in low pH ecosystems, effectively neutralizing the acidity environment, and making it more amenable for other methanogens. This, in turn, would allow people to harness the pure methane produced at landfills or through cow waste. Evidently, the implications of ''M. barkeri'' are those aligned with potential alternative energy and investment.


Notes


References


Further reading

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External links


Type strain of ''Methanosarcina barkeri'' at Bac''Dive'' – the Bacterial Diversity Metadatabase
{{Taxonbar, from=Q4044137 Euryarchaeota