Methanosarcina barkeri

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

Corrinoid-Dependent Mechanism of Acetogenesis from Methanol

Abstract: More than 13 reactions are catalyzed by corrinoid-containing enzymes in prokaryotes and eukaryotes. These reactions were reviewed previously (Stadtman, 1971; Halpern, 1985) but some additional corrinoid-dependent reactions have been discovered since then. For example, the methanol conversion into methane proceeds via a corrinoid-dependent methyltransferase (van der Meijden et al., 1984a). The enzyme from Methanosarcina barkeri provides the methyl group from methanol to the specific methanogenic cofactor 2-mercaptoethanesulfonic acid (HS-CoM) after the protein is reductively activated by H2 and ATP. That enzyme revealed an α2β structure and it contained 3–4 mol loosely bound corrinoid per mole of protein. In vitro studies with mixed cell-free extracts of Methanosarcina barkeri and Eubacterium limosum indicated that the acetogenic bacterium also possesses a methylated corrinoid enzyme. This enzyme was demethylated in the presence of methylcobalamin: coenzyme M methyltransferase from the methanogenic bacterium with concomitant formation of methyl-coenzyme M (van der Meijden et al., 1984b).

Substrate-dependent incorporation of carbon and hydrogen for lipid biosynthesis by Methanosarcina barkeri.

Abstract: Dual stable isotope probing has been used to infer rates of microbial biomass production and modes of carbon fixation. In order to validate this approach for assessing archaeal production, the methanogenic archaeon Methanosarcina barkeri was grown either with H2 , acetate or methanol with D2 O and 13 C-dissolved inorganic carbon (DIC). Our results revealed unexpectedly low D incorporation into lipids, with the net fraction of water-derived hydrogen amounting to 0.357±0.042, 0.226±0.003 and 0.393±0.029 for growth on H2 /CO2 , acetate and methanol, respectively. The variability in net water H assimilation into lipids during growth of M. barkeri on different substrates is possibly attributed to different Gibbs free energy yields, such that higher energy yield promoted the exchange of hydrogen between medium water and lipids. Because NADPH likely serves as the portal for H transfer, increased NADPH production and/or turnover associated with high energy yield may explain the apparent differences in net water H assimilation into lipids. The variable DIC and water H incorporation into M. barkeri lipids imply systematic, metabolic patterns of isotope incorporation and suggest that the ratio of 13 C-DIC vs D2 O assimilation in environmental samples may serve as a proxy for microbial energetics in addition to microbial production and carbon assimilation pathways. This article is protected by copyright. All rights reserved.

Pre-transfer Editing of Serine Hydroxamate within the Active Site of Methanogenic-type Seryl-tRNA Synthetase

Abstract: Aminoacyl-tRNA synthetases (aaRSs) maintain fidelity of protein synthesis by matching only cognate amino acid-tRNA pairs. Aminoacylation occurs through activation of amino acid to yield aminoacyl-adenylate followed by transfer of acyl-moiety to tRNA. Error-prone aaRSs achieve high level of accuracy using inherent hydrolytic activities towards noncognate aminoacyl-adenylate or misacylated tRNA (pre- and post-transfer editing).Seryl-tRNA synthetases can be divided into two structurally different types: canonical and methanogenic-type. Both types have been shown to efficiently activate serine analogue serine hydroxamate (SerHX). Moreover, this analogue has been also eliminated by pre-transfer editing within the canonical synthetic site of yeast SerRS. Here we show that methanogenic-type SerRS from Methanosarcina barkeri clears misactivated SerHX similarly as the yeast enzyme: SerHX-adenylate is not expelled into solution, but is enzymatically hydrolyzed in a tRNA-independent manner. Since the enzyme lacks domain specialized in editing, this shows that methanogenic-type catalytic core is also capable to perform pre-transfer editing.

Anaerobic degradation of sulphite evaporator condensate in a fixed-bed loop reactor by a defined bacterial consortium

Abstract: After elucidating the composition of an anaerobic bacterial enrichment culture treating sulphite evaporator condensate (SEC), an effluent in the pulp and paper industry, we built up stepwise a defined mixed culture to convert the organic constituents of SEC (acetate, methanol, furfural) to methane and CO2 In batch cultures Desulfovibrio furfuralis and Methanobacterium bryantii degraded furfural in the absence of sulphate via inter-species H2 transfer yielding 042 mol methane and 187 mol acetate/mol furfural degraded When Methanosarcina barkeri was added to this diculture, acetate was also transformed to methane yielding 093 mol methane/mol acetate converted This consortium (D furfuralis, Methanobacterium bryantii and Methanosarcina barkeri) degraded furfural in continuous culture (fixed-bed loop reactor) to 92%, but the conversion of acetate was only 67% The conversion of acetate could be further improved to 86% by adding 10 mm sulphate to the medium This resulted in a space time yield of 109 g chemical oxygen demand (COD)/1 per day for the overall conversion With a consortium consisting of M barkeri, Methanobrevibacter arboriphilus, Methanosaeta concilii and D furfuralis, a synthetic SEC could be degraded at a space time yield of 1335 g COD/1 per day This defined culture degraded all the constituents of SEC at an efficiency of almost 90% compared to an enrichment culture under identical conditions