''Methanosarcina acetivorans'' is a versatile
methane producing microbe which is found in such diverse environments as oil wells, trash dumps, deep-sea hydrothermal vents, and oxygen-depleted sediments beneath kelp beds. Only ''M. acetivorans'' and microbes in the genus ''
Methanosarcina
''Methanosarcina'' is a genus of euryarchaeote archaea
Archaea ( ; singular archaeon ) is a domain of single-celled organisms. These microorganisms lack cell nuclei and are therefore prokaryotes. Archaea were initially classified as ...
'' use all three known metabolic pathways for
methanogenesis. Methanosarcinides, including ''M. acetivorans'', are also the only
archaea capable of forming multicellular colonies, and even show cellular differentiation. The genome of ''M. acetivorans'' is one of the largest archaeal
genomes
In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding g ...
ever sequenced. Furthermore, one strain of ''M. acetivorans'', ''M. a. C2A'', has been identified to possess an F-type
ATPase (unusual for archaea, but common for bacteria,
mitochondria and
chloroplasts
A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in ...
) along with an A-type ATPase.
[Regina Saum et al.]
The F1FO ATP synthase genes in ''Methanosarcina acetivorans'' are dispensable for growth and ATP synthesis
in: FEMS Microbiology Letters Vol. 300 Issue 2, November 2009, P. 230–236, DOI: 10.1111/j.1574-6968.2009.01785.x
Metabolism
''M. acetivorans'' has been noted for its ability to
metabolize
Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...
carbon monoxide
Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simple ...
to form
acetate and
formate.
It can also
oxidize
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...
carbon monoxide into
carbon dioxide
Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
. The carbon dioxide can then be converted into
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 Ea ...
in a process which ''M. acetivorans'' uses to conserve energy.
It has been suggested that this pathway may be similar to metabolic pathways used by primitive cells.
However, in the presence of minerals containing iron sulfides, as might have been found in sediments in a primordial environment, acetate would be catalytically converted into acetate thioester, a sulfur-containing derivative. Primitive microbes could obtain biochemical energy in the form of
adenosine triphosphate
Adenosine triphosphate (ATP) is an organic compound that provides energy to drive many processes in living cells, such as muscle contraction, nerve impulse propagation, condensate dissolution, and chemical synthesis. Found in all known forms o ...
(ATP) by converting acetate thioester back into acetate using PTS and ACK, which would then be converted back into acetate thioester to complete the process. In such an environment, a primitive "protocell" could easily produce energy through this metabolic pathway, excreting acetate as waste. Furthermore, ACK catalyzes the synthesis of ATP directly. Other pathways generate energy from ATP only through complex multi-enzyme reactions involving protein pumps and osmotic imbalances across a membrane.
History
''M. acetivorans'' was isolated in 1984 from marine sediment obtained at
Scripps Canyon
Scripps Canyon is a narrow underwater gorge located in the Pacific Ocean off the coast of southern California, United States. The canyon is approximately long and joins to La Jolla Canyon offshore.
It is located near the Scripps Institution of ...
.
See also
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RNA world
The RNA world is a hypothetical stage in the evolutionary history of life on Earth, in which self-replicating RNA molecules proliferated before the evolution of DNA and proteins. The term also refers to the hypothesis that posits the existen ...
*
Origin of life
In biology, abiogenesis (from a- 'not' + Greek bios 'life' + genesis 'origin') or the origin of life is the natural process by which life has arisen from non-living matter, such as simple organic compounds. The prevailing scientific hypothes ...
References
Further reading
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External links
Putting Life's Puzzle Together from Astrobiology Magazine (17 May 2006)Type strain of ''Methanosarcina acetivorans'' at Bac''Dive'' – the Bacterial Diversity Metadatabase
{{Taxonbar, from=Q1946250
Origin of life
Metabolism
Organisms living on hydrothermal vents
Euryarchaeota
Archaea described in 1986