Methanosarcina acetivorans

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 use all three known metabolic pathways for methanogenesis.[1] 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 ever sequenced.[2] 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) along with an A-type ATPase.[3]

Methanosarcina acetivorans
Scientific classification
Domain:
Archaea
Kingdom:
Euryarchaeota
Phylum:
Euryarchaeota
Class:
Methanomicrobia
Order:
Methanosarcinales
Family:
Methanosarcinaceae
Genus:
Methanosarcina
Species:
M. acetivorans
Binomial name
Methanosarcina acetivorans
Sowers et al. 1986

Metabolism

M. acetivorans has been noted for its ability to metabolize carbon monoxide to form acetate and formate.[4] It can also oxidize carbon monoxide into carbon dioxide. The carbon dioxide can then be converted into methane in a process which M. acetivorans uses to conserve energy.[5] It has been suggested that this pathway may be similar to metabolic pathways used by primitive cells.[6]

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 (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.[7]

See also
  • RNA world
  • Origin of life

References
  1. Galagan JE; Nusbaum C; Roy A; Endrizzi MG; Macdonald P; FitzHugh W; Calvo S; et al. (2002). "The Genome of M. acetivorans Reveals Extensive Metabolic and Physiological Diversity". Genome Research. 12 (4): 532–42. doi:10.1101/gr.223902. PMC 187521. PMID 11932238.
  2. http://microbewiki.kenyon.edu/index.php/Methanosarcina Microbewiki: Methanosarcina
  3. 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
  4. Rother M; Metcalf WW (November 2004). "Anaerobic growth of Methanosarcina acetivorans C2A on carbon monoxide: an unusual way of life for a methanogenic archaeon". Proceedings of the National Academy of Sciences USA. 101 (48): 16929–16934. Bibcode:2004PNAS..10116929R. doi:10.1073/pnas.0407486101. PMC 529327. PMID 15550538.
  5. Lessner DJ; Li L; Li Q; Rejtar T; Andreev VP; Reichlen M; Hill K; et al. (November 2006). "An unconventional pathway for reduction of CO2 to methane in CO-grown Methanosarcina acetivornas revealed by proteomics". Proceedings of the National Academy of Sciences USA. 103 (47): 17921–17926. Bibcode:2006PNAS..10317921L. doi:10.1073/pnas.0608833103. PMC 1693848. PMID 17101988.
  6. Ferry JG; House CH (June 2006). "The stepwise evolution of early life driven by energy conservation". Mol Biol Evol. 23 (6): 1286–1292. doi:10.1093/molbev/msk014. PMID 16581941.
  7. Sowers KR; Baron SF; Ferry JG (May 1984). "Methanosarcina acetivorans sp. nov., an Acetotrophic Methane-Producing Bacterium Isolated from Marine Sediments". Applied and Environmental Microbiology. 47 (5): 971–978. Bibcode:1984ApEnM..47..971S. doi:10.1128/AEM.47.5.971-978.1984. PMC 240030. PMID 16346552.

Further reading
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