Methanosarcina barkeri

About: Methanosarcina barkeri is a research topic. Over the lifetime, 703 publications have been published within this topic receiving 32151 citations.

Conversion of Methanol and Methylamines to Methane and Carbon Dioxide

Abstract: The first report on methane formation from a methylated one-carbon compound, notably methanol, goes back to 1920 (Groenewegen, 1920). In the thirties, methylotrophic methanogens were systematically studied in the laboratory of Kluy ver and Van Niel (1936). Here, Barker (1936) enriched an organism, then called Methanococcus mazei, which was capable of growth not only on methanol, but also on butanol and acetone. The organism was not pure and the original cultures were lost. Only about 40 years later, the methanogen that met the original description was reisolated and renamed Methanosarcina mazei (Mah, 1980; Mah and Kuhn, 1984). The first methylotroph obtained in axenic culture, and in fact one of the first pure methanogenic species, was isolated by Schnellen (1936), a student of Kluyver. Again, the original cultures of the organism, Methanosarcina barkeri, were lost. M. barkeri has been reisolated as a number of distinct strains from a variety of sources. The type strain, MS, was obtained by Bryant in 1966 (Bryant, 1966; Bryant and Boone, 1987). Biochemically, M. barkeri is the best studied methylotrophic methanogen and most of the work reviewed in this chapter refers to it.

Characterization and purification of the membrane-bound ATPase of the archaebacterium Methanosarcina barkeri.

Abstract: Membrane-bound ATPase was found in membranes of the archaebacterium Methanosarcina barkeri. The ATPase activity required divalent cations, Mg2+ or Mn2+, and maximum activity was obtained at pH 5.2. The activity was specifically stimulated by HSO3- with a shift of optimal pH to 5.8, and N,N'-dicyclohexylcarbodiimide inhibited ATP hydrolysis. The enzyme could be solubilized from membranes by incubation in 1 mM Tris-maleate buffer (pH 6.9) containing 0.5 mM EDTA. The solubilized ATPase was purified by DEAE-Sepharose and Sephacryl S-300 chromatography. The molecular weight of the purified enzyme was estimated to be 420,000 by gel filtration through Sephacryl S-300. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate revealed two classes of subunit, Mr 62,000 (alpha) and 49,000 (beta) associated in the molar ratio 1:1. These results suggest that the ATPase of M. barkeri is similar to the F0F1 type ATPase found in many eubacteria.

One-Carbon Metabolism in Methanogens: Evidence for Synthesis of a Two-Carbon Cellular Intermediate and Unification of Catabolism and Anabolism in Methanosarcina barkeri

Abstract: One-carbon metabolic transformations associated with cell carbon synthesis and methanogenesis were analyzed by long- and short-term 14CH3OH or 14CO2 incorporation studies during growth and by cell suspensions. 14CH3OH and 14CO2 were equivalently incorporated into the major cellular components (i.e., lipids, proteins, and nucleic acids) during growth on H2-CO2-methanol. 14CH3OH was selectively incorporated into the C-3 of alanine with decreased amounts fixed in the C-1 and C-2 positions, whereas 14CO2 was selectively incorporated into the C1 moiety with decreasing amounts assimilated into the C-2 and C-3 atoms. Notably, 14CH4 and [3-14C]alanine synthesized from 14CH3OH during growth shared a common specific activity distinct from that of CO2 or methanol. Cell suspensions synthesized acetate and alanine from 14CO2. The addition of iodopropane inhibited acetate synthesis but did not decrease the amount of 14CH3OH or 14CO2 fixed into one-carbon carriers (i.e., methyl coenzyme M or carboxydihydromethanopterin). Carboxydihydromethanopterin was only labeled from 14CH3OH in the absence of hydrogen. Cell extracts catalyzed the synthesis of acetate from 14CO (∼1 nmol/min per mg of protein) and an isotopic exchange between CO2 or CO and the C-1 of pyruvate. Acetate synthesis from 14CO was stimulated by methyl B12 but not by methyl tetrahydrofolate or methyl coenzyme M. Methyl coenzyme M and coenzyme M were inhibitory to acetate synthesis. Cell extracts contained high levels of phosphotransacetylase (>6 μmol/min per mg of protein) and acetate kinase (>0.14 μmol/min per mg of protein). It was not possible to distinguish between acetate and acetyl coenzyme A as the immediate product of two-carbon synthesis with the methods employed.

Molecular, genetic, and biochemical characterization of the serc gene of methanosarcina barkeri fusaro

Abstract: The Methanosarcina barkeri serC gene, encoding phosphoserine aminotransferase, was cloned by complementation of an Escherichia coli serC mutant, and its nucleotide sequence was determined. The M. barkeri SerC protein shares significant homology with other known SerC proteins. E. coli serC hosts carrying the cloned gene express phosphoserine aminotransferase activity, verifying the function of this gene.