A Microbial Biorealm page on the genus Methanosarcina mazei
Higher order taxa
Archaea; Euryarchaeota; Methanomicrobia; Methanosarcinales; Methanosarcinacaea; Methanosarcina, mazei [Others may be used. Use NCBI link to find]
Description and significance
Methanosarcina mazei is a versatile anærobic archaeobacter (10) which is found in semi aquatic environments such as sewage receptacles and anoxygenic, moist soils (ie riverbeds and ponds) (6). M.mazei, much like other Methanosarcina spp. Have both eukaryotic and prokaryotic features (15). Reasons for this will be discussed below. Early on prior to the latter 1980's, M.mazei was labeled as a Methanococcus spp. But after reevaluation, it placed in the Methanosarcina spp. Taxonomy(1). This reclassification was due to confusion from the dual nature of M.mazei much like other Methanosarcina spp. in that it can exist either individually in colonies or as large-sized cysts (1, 7, 9, 11). This quality is unique to Methanosarcina spp out of all archaea (7). This variation in culture development is dependent on many factors including salinity (9). In intermediate salinity (0.4M NaCl – 1.0 NaCl), M.mazei does not aggregate, but in either direction, more extreme salinity allows/causes M.mazei to aggregate (9). This dual behaviour is relatively unique even for other Methanosarcina spp. This is because the others do not naturally disaggregate and in fact have difficulty living singly (9).
The genome of M.mazei has been sequenced. With 3436 Genes, 3370 ORFs, and 66 known structural RNAs, there are no known pseudo genes (16). In terms of the organization of its DNA, the M.mazei genome is made of circular dsDNA (16) and is the second largest of all Methanosarcina spp.(6). In fact, the extrachromosomal element of M.mazei is 6.7 times larger then that of M.acetivorans(6). The genomes of methanosarcina spp. have been well characterized and M.mazei is no exception. Of all the Methanosarcinae, only M.mazei and M.acetivorans have been shown to carry transposable elements (4). M. mazei is also relatively unique along with its cousins because of the organization of its chaperonins. These microbes are in posession of both the eukaryotic and prokaryotic type chaperone protein structures. Group II, which is exclusive to archaeal and eukaryotic organisms has been transferred down vertically (5). The posession of group I, the category found only in bacterial cytosol and mitochondria/chloroplasts seem to be horizontally transferred (5). This is evident of the supposed relationship archaea and bacteria seem to have: a unidirectional transfer of genetic material (5, 14, 15). There is even evidence that 20-33% of the M.mazei genome has been horizontally transferred (5). This percentage of additional genetic material may account for the larger sized genome found therein.
Cell structure and metabolism
Individual cells of M.mazei are small, simple, cocci (1) which are capable of reversible aggregation (3,7). As noted above, the aggregation of M.mazei forms large, dense cysts (7). When ruptured, the burst with many cells (9). There is evidence that disaggregation is guided by a protein, Dag -disaggregase, which shows control of the extracellular matrix (ECM) created by this microbe (7). The ECM of this microbe is comprised of an outer layer made methanochondroitin: a mixture of glucaronic acid, glucose, galactosamine, mannose (<100nm thick) and a much thinner inner S-layer made mostly of protein (9). Methanosarcinal chondroitin is similar to eukaryotic chondroitin. Also as stated previously, this aggregation/disaggregation proces is a response to environmental stimuli such as salinity for example (7). While M.mazei is halophilic, it lacks the PGP-Me found in the cell walls and membranes hyper-halophilic archaea(11).
M.mazei is capable of every metabolic activity of which which other Methanosarcina spp. are capable (7). The substrates on which M.mazei is capable of surviving are H2/CO2, acetate, all methylamines, and methanol (7). This differs from M.acetivorans, which cannot subsist on H2/CO2 reduction for it lacks a functional H2 reducer (6). These options prive a certain versatility to M.mazei which enables It to live in a multitude of substrates and environments (10). M.mazei is also a N-fixing organism. It has been shown to fix N when none is available from environmental methylamines (12). When they are available however, it metabolizes them and ignores available, fixable N in the environment(12). This process is guided by the mtmB2C2 operon (12). All of the metabolic processes carrid out by M.mazei end with the production of CH4 (3).
Methanogenic ecosystems constitute a food chain with three distinguishable trophic levels as fermentable substrates are anaerobically degraded (2). Because of the variety of metabolic options open to M.mazei (7), its presence strengthens an ecosystem and in fact leads to positive selection over the long term (2). This viability makes M.mazei useful in the treatment of organic waste over long periods of time (6, 2)
No evidence for pathology could be cited.
It has been shown that M.mazei can be cultured in methanogenic reactors successfully over long periods of time (2). In conjunction with an ability to digest organic waste, being at the very bottom stage of organic waste breakdown in a semiaquatic environment (2, 10), M.mazei and its cousins could be used in a waste treatment process. This has promise for a clean treatment of human waste. Furthermore, because M.mazei is a methanogen (3), it is possible to harness that metabolic endpoint for the production of alternative fuels.
At the moment, concern for the state of the environment has led to a great deal of research for Methanosarcina spp and especially for M.mazei which is one of the simplest to keep in culture (10). There has been a great deal of recent work on the metabolic pathways involved in methane production (13) and acetate/methanol uptake (10, 3). So much energy has been put into disaggregation of M.mazei and its clan because of the difficulties involved in studying a microbe which cannot grow successfully as individuals, but offers great benefits from study (9). Another realm of study for M.mazei is work done on Hsp70 and the double chaperone group system. The coexistence of both protein systems offer study of M.mazei as a model for substrate specificity in each each system (9). Understanding the behaviour of prokaryotic and eukaryotic protein chaperone systems elucidates a great deal of understanding for the fundamentals of protein processing in vivo. It is hardly a mistake to suggest that Methanosarcina spp. offer great promise for future research, and that M.mazei is presently an active participant in present research.
[(1) Conway de Macario, E., Macario, A.J.L., Mok, T., Beveridge, T.J. “Immunochemistry and Localiztion of the Enzyme Disaggregatase in Methanosarcina mazei”. Journal of Bacteriology. 1993 May: 175(10); 3115-3120.]
[(2)Fernandez, A., Huang, Suiying, Seston, S., Xing, J., Hickey, R., Criddle, C., Tiedje, J. “How stable is Stable? Function versus Community Composition”. Applied and Environmental Microbiology. 1999 Aug: 65(8); 3697-3704.]
[(3)Janssen, P., Frenzel, P. “Inhibition of Methanogenesis by Methyl Fluoride: Studies of Pure and Defined Mixed Cultures of Anaerobic Bacteria and Archaea”. Applied and Environmental Microbiology. 1997 Nov: 63(11); 4552-4557.]
[(4)Rest, J.S., Mindell, D.P. “Retroids in Archara: Phylogeny and Lateral Origins”. Molecular Biology and Evolution. 2003: 20(7); 1134-1142.]
(5)Klunker, D., Haas, B., Hirtreiter, A., Figueiredo, L., Naylor, D., Pfeifer, G., Müller, V., Deppenmeier, U., Gottschalk, G, Hartl, F.U., Hayer-Hartl, M. “Coexistence of Group 1 and Group II Chaperonins in the Archaeon Methanosarcina mazei.” The Journal of Biological Chemistry. 2003 Aug: 278(35); 33256-33267.]
[(6)Maeder, D.L., Anderson, I., Brettin, T.S., Bruce, D.C., Gilna, P. Han, C.S., Lapidus, A., Metcalf, W.W., Saunders, E., Tapia, R., Sowers, K.R. The Methanosarcina barkeri Genome: Comparative Analysis with Methanosarcina acetivorans and Methanosarcina mazei Reveals Extensive Rearrangement within Methanosarcinal Genomes. Journal of Bacteriology. 2006 Nov: 188(22); 7922-7931.]
[(7)Osumi, N.,Kakehashi, Y., Matsumoto, S., Nagaoka, K, Sakai, J., Miyashita, K.,Kimura, M. Asakawa, S. “Identification of the gene for disaggregatase from Methanosarcina mazei”. Archaea. 2008 April: 2, 185–191.]
[(8)Pfluger, K., Baumann, S., Gottschalk, G., Lin, W., Santos, H., Muller, V. “Lysine-2,3-Aminomutase and β-Lysine Acetyltransferase Genes of Methanogenic Archaea Are Salt Induced and Are Essential for Biosynthesis of N-Acetyl-β-Lysine and Growth at High Salinity”. Applied and Environmental Microbiology. 2003 Oct: 69(10); 6047-6055.] [(9)Sowers, K.R., Boone, J.E., Gunsalus, R.P. “Disaggregation of Methanosarcina spp. and Growth as Single Cells at Elevated Osmolarity”. Applied and Environmental Microbiology. 1993 Nov: 59(11); 3832-3839.]
[(10)Tatton, M.J., Archer, D.B., Powell, G.E., Parker, M.L. “Methanogenesis from Ethanol by Defined Mixed Continuous Cultures”.Applied and Environmental Microbiology. 1989 Feb: 55(2); 440-445.]
[(11)Tenchov, B., Vescio, E., Sprott, G.D., Zeidel, M.L., Mathai, J.C. “Salt Tolerance of Archaeal Extremely Halophilic Lipid Membranes”. The Journal of Biological Chemistry. 2006 April: 281(15); 10016-10023.]
[(12)Veit, K., Ehlers, C., Schmitz, R.A. “Effect of Nitrogen and Carbon Sources on Transcription of Soluble Methyltransferases in Methanosarcina mazei Strain Gö1”. Journal of Bacteriology. 2005 Sept: 187(17); 6147-6154.]
[(13)Westerman, P., Ahring, B., Mah, R. “Acetate Production by Methanogenic Bacteria”. Applied and Environmental Microbiology. 1989 Sep: 55(9); 2257-2261.]
[(14)Zmijewski, M.A., Skorko-Glonek, J., Tanfani, F., Banecki, B., Kotlarz, A., Macario, A.L.J., Pipinska, B. “The DnaK chaperones from the archaeon Methanosarcina mazei and the bacterium Escherichia coli have different substrate specificities. Acta Biochimica Polonica. 2005: 54(2); 509-522.]
[(15)Zmijewski, M.A., Skorko-Glonek, J., Tanfani, F., Banecki, B., Kotlarz, A., Macario, A.L.J., Pipinska, B. “Structural basis of the interspecies interaction between the chaperone DnaK(Hsp70) and the co-chaperone GrpE of archaea and bacteria”. Acta Biochimica Polonica. 2007: 54(2); 245-252.]
[(16) “Methanosarcina mazei Go”. http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=192952&lvl=3&keep=1&srchmode=1&unlock&lin=s. NCBI Taxonomy Browser. 2008 Dec 17; 7:14:24PM.]
Edited by Nathan Yetton of Emily Lilly at University of Massachusetts Dartmouth.