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Methanosarcina barkeri
About: Methanosarcina barkeri is a research topic. Over the lifetime, 703 publications have been published within this topic receiving 32151 citations.
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TL;DR: The pterin compound lumazine inhibited the growth of several methanogenic archaea completely at a concentration of ≤ 0.6 mM and was bacteriocidal for Methanobacterium thermoautotrophicum strain Marburg, suggesting it may be useful in probing the methanogenesis pathway or in selecting against methanogens.
Abstract: The pterin compound lumazine [2, 4-(1H, 3H)-pteridinedione] inhibited the growth of several methanogenic archaea completely at a concentration of ≤ 0.6 mM and was bacteriocidal for Methanobacterium thermoautotrophicum strain Marburg. In contrast, growth of two non-methanogenic archaea, several eubacteria, and one eukaryote was not strongly affected at much higher concentrations. In washed-cell suspensions, methanogenesis from H2 and CO2 by Mb. thermoautotrophicum or from H2 and methanol by Methanosarcina barkeri was inhibited by addition of lumazine. In cell-free extracts of Mb. thermoautotrophicum, H2-driven methane production from CO2 or CH3-S-CoM was completely inhibited by 0.6 mM lumazine. The results suggest that the compound may be useful in probing the methanogenesis pathway or in selecting against methanogens.
24 citations
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TL;DR: The results provide compelling evidence for a direct binding of CoM‐SH to the [4Fe–4S] cluster in the active site of the enzyme.
24 citations
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TL;DR: In this article, the active site histidine residue was identified by site-directed mutagenesis to be His84 in the MtrA sequence that contains three histidines.
Abstract: The energy-conserving corrinoid-containing MtrA-H complex from Methanobacterium thermoautotrophicum is composed of eight different subunits of which MtrA harbors the corrinoid prosthetic group. EPR spectroscopic evidence has recently been presented for a histidine residue as a cobalt ligand of the cobamide [Harms, U. & Thauer, R. K. (1996a) Eur J. Biochem. 241, 149–154]. This active site histidine was now identified by site-directed mutagenesis to be His84 in the MtrA sequence that contains three histidines. This result was substantiated by sequence comparison of MtrA froin M. thermoautotrophicum, Methanococcus jannaschii, and Methanopyrus kandleri and of MtxA from Methanosarcina barkeri showing that only His84 is conserved. For comparison, the DNA sequences of the mtrEDCBAGH operon in M. kundleri and of the mtxXAH operon in M. barkeri were determined.
24 citations
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TL;DR: In this paper, the authors reported that Rhodopseudomonas palustris was able to directly act as a living photosensitizer to drive CO2 to CH4 conversion by Methanosarcina barkeri under illumination after coculturing.
Abstract: The direct conversion of CO2 to value-added chemical commodities, thereby storing solar energy, offers a promising option for alleviating both the current energy crisis and global warming. Semiconductor-biological hybrid systems are novel approaches. However, the inherent defects of photocorrosion, photodegradation, and the toxicity of the semiconductor limit the application of these biohybrid systems. We report here that Rhodopseudomonas palustris was able to directly act as a living photosensitizer to drive CO2 to CH4 conversion by Methanosarcina barkeri under illumination after coculturing. Specifically, R. palustris formed a direct electric syntrophic coculture with M. barkeri. Here, R. palustris harvested solar energy, performed anoxygenic photosynthesis using sodium thiosulfate as an electron donor, and transferred electrons extracellularly to M. barkeri to drive methane generation. The methanogenesis of M. barkeri in coculture was a light-dependent process with a production rate of 4.73 ± 0.23 μM/h under light, which is slightly higher than that of typical semiconductor-biohybrid systems (approximately 4.36 μM/h). Mechanistic and transcriptomic analyses showed that electrons were transferred either directly or indirectly (via electron shuttles), subsequently driving CH4 production. Our study suggests that R. palustris acts as a natural photosensitizer that, in coculture with M. barkeri, results in a new way to harvest solar energy that could potentially replace semiconductors in biohybrid systems.
24 citations
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TL;DR: It is demonstrated that Methanosarcina species could play an important role in the long-term bioremediation of uranium-contaminated aquifers after depletion of Fe(III) oxides limits the growth of Geobacter species and suggested that Methanoarcina have the potential to influence uranium geochemistry in a diversity of anaerobic sedimentary environments.
Abstract: Previous studies of acetate-promoted bioremediation of uranium-contaminated aquifers focused on Geobacter because no other microorganisms that can couple the oxidation of acetate with U(VI) reduction had been detected in situ. Monitoring the levels of methyl CoM reductase subunit A (mcrA) transcripts during an acetate-injection field experiment demonstrated that acetoclastic methanogens from the genus Methanosarcina were enriched after 40 days of acetate amendment. The increased abundance of Methanosarcina corresponded with an accumulation of methane in the groundwater. In order to determine whether Methanosarcina species could be participating in U(VI) reduction in the subsurface, cell suspensions of Methanosarcina barkeri were incubated in the presence of U(VI) with acetate provided as the electron donor. U(VI) was reduced by metabolically active M. barkeri cells; however, no U(VI) reduction was observed in inactive controls. These results demonstrate that Methanosarcina species could play an important role in the long-term bioremediation of uranium-contaminated aquifers after depletion of Fe(III) oxides limits the growth of Geobacter species. The results also suggest that Methanosarcina have the potential to influence uranium geochemistry in a diversity of anaerobic sedimentary environments.
24 citations