Hydrogenotrophic methanogenesis in Methanosarcina thermophila

2020 ◽  
Author(s):  
Nina Lackner
Keyword(s):  
Methanosarcina Thermophila ◽  
Hydrogenotrophic Methanogenesis

scholarly journals Hydrogenotrophic Methanogenesis and Autotrophic Growth ofMethanosarcina thermophila

Archaea ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Nina Lackner ◽  
Anna Hintersonnleitner ◽  
Andreas Otto Wagner ◽  
Paul Illmer
Keyword(s):  
Carbon Dioxide ◽  
Rna Sequencing ◽  
Methane Production ◽  
Fresh Medium ◽  
Autotrophic Growth ◽  
Methanosarcina Thermophila ◽  
Hydrogenotrophic Methanogenesis ◽  
16S Rna ◽  
Genomic Analyses ◽  
Production Growth

Although Methanosarcinales are versatile concerning their methanogenic substrates, the ability ofMethanosarcina thermophilato use carbon dioxide (CO2) for catabolic and anabolic metabolism was not proven until now. Here, we show thatM. thermophilaused CO2to perform hydrogenotrophic methanogenesis in the presence as well as in the absence of methanol. During incubation with hydrogen, the methanogen utilized the substrates methanol and CO2consecutively, resulting in a biphasic methane production. Growth exclusively from CO2occurred slowly but reproducibly with concomitant production of biomass, verified by DNA quantification. Besides verification through multiple transfers into fresh medium, the identity of the culture was confirmed by 16s RNA sequencing, and the incorporation of carbon atoms from13CO2into13CH4molecules was measured to validate the obtained data. New insights into the physiology ofM. thermophilacan serve as reference for genomic analyses to link genes with metabolic features in uncultured organisms.

Exemplar Abstract for Methanosarcina thermophila Zinder et al. 1985.

2003 ◽  
Author(s):  
Charles Thomas Parker ◽  
Kara Mannor ◽  
George M Garrity ◽  
Dorothea Taylor
Keyword(s):  
Methanosarcina Thermophila

The treatment of iron oxalate leach liquors in a UASB with sulfate reduction

1997 ◽  
Vol 36 (6-7) ◽  
pp. 383-390 ◽  
Author(s):  
J. E. Teer ◽  
D. J. Leak ◽  
A. W. L. Dudeney ◽  
A. Narayanan ◽  
D. C. Stuckey
Keyword(s):  
Bacterial Species ◽  
Upflow Anaerobic Sludge Blanket ◽  
Anaerobic Sludge ◽  
Desulfovibrio Vulgaris ◽  
Hydrogenotrophic Methanogenesis ◽  
Irreversible Effects ◽  
High Concentrations ◽  
A Minor ◽  
Anaerobic Sludge Blanket ◽  
Reducing Bacteria

The presence of small amounts of iron (>0.013% Fe) in sand creates problems in the manufacture of high quality glass. Removal by hot sulphuric acid is possible, but creates environmental problems, and is costly. Hence organic acids such as oxalic have been investigated since they are effective in removing iron, and can be degraded anaerobically. The aim of this work was to identify key intermediates in the anaerobic degradation of oxalate in an upflow anaerobic sludge blanket reactor (UASB) which was removing iron from solution in the sulphide form, and to determine the bacterial species involved. 2-bromoethanesulfonic acid (BES) and molybdenum were selected as suitable inhibitors for methanogenic and sulphate reducing bacteria (SRB) respectively. 40mM molybdenum was used to inhibit the SRB in a reactor with a 12hr HRT. Total SRB inhibition took place in 20 hrs, with a complete breakthrough of influent sulphate. The lack of an immediate oxalate breakthrough confirmed Desulfovibrio vulgaris subspecies oxamicus was not the predominant oxalate utilising species. Nevertheless, high concentrations of molybdenum were found to inhibit oxalate utilising bacteria in granular reactors but not in suspended population reactors; this observation was puzzling, and at present cannot be explained. Based on the intermediates identified, it was postulated that oxalate was degraded to formate by an oxalate utilising bacteria such as Oxalobacter formigenes, and the formate used by the SRBs to reduce sulphate. Acetate, as a minor intermediate, existed primarily as a source of cell carbon for oxalate utilising bacteria. Methanogenic inhibition identified that 62% of the CH4 in the reactor operated at 37°C originated from hydrogenotrophic methanogenesis, whilst this figure was 80% at 20°C. Possible irreversible effects were recorded with hydrogenotrophic methanogens.

scholarly journals Characterization of the Acetate Binding Pocket in the Methanosarcina thermophila Acetate Kinase

2005 ◽  
Vol 187 (7) ◽  
pp. 2386-2394 ◽  
Author(s):  
Cheryl Ingram-Smith ◽  
Andrea Gorrell ◽  
Sarah H. Lawrence ◽  
Prabha Iyer ◽  
Kerry Smith ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Binding Site ◽  
Binding Pocket ◽  
Acetate Kinase ◽  
Phosphoryl Group ◽  
Acetyl Phosphate ◽  
Hydrophobic Pocket ◽  
Methanosarcina Thermophila ◽  
Methyl Group ◽  
Substrate Binding Sites

ABSTRACT Acetate kinase catalyzes the reversible magnesium-dependent synthesis of acetyl phosphate by transfer of the ATP γ-phosphoryl group to acetate. Inspection of the crystal structure of the Methanosarcina thermophila enzyme containing only ADP revealed a solvent-accessible hydrophobic pocket formed by residues Val93, Leu122, Phe179, and Pro232 in the active site cleft, which identified a potential acetate binding site. The hypothesis that this was a binding site was further supported by alignment of all acetate kinase sequences available from databases, which showed strict conservation of all four residues, and the recent crystal structure of the M. thermophila enzyme with acetate bound in this pocket. Replacement of each residue in the pocket produced variants with Km values for acetate that were 7- to 26-fold greater than that of the wild type, and perturbations of this binding pocket also altered the specificity for longer-chain carboxylic acids and acetyl phosphate. The kinetic analyses of variants combined with structural modeling indicated that the pocket has roles in binding the methyl group of acetate, influencing substrate specificity, and orienting the carboxyl group. The kinetic analyses also indicated that binding of acetyl phosphate is more dependent on interactions of the phosphate group with an unidentified residue than on interactions between the methyl group and the hydrophobic pocket. The analyses also indicated that Phe179 is essential for catalysis, possibly for domain closure. Alignments of acetate kinase, propionate kinase, and butyrate kinase sequences obtained from databases suggested that these enzymes have similar catalytic mechanisms and carboxylic acid substrate binding sites.

scholarly journals ANME-1 archaea drive methane accumulation and removal in estuarine sediments

2020 ◽  
Author(s):  
Richard Kevorkian ◽  
Sean Callahan ◽  
Rachel Winstead ◽  
Karen G. Lloyd
Keyword(s):  
16S Rrna ◽  
Sulfate Reducing Bacteria ◽  
Low Energy ◽  
Estuarine Sediments ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Sulfate Reducing ◽  
Hydrogenotrophic Methanogenesis ◽  
Natural Settings ◽  
Reducing Bacteria

AbstractUncultured members of the Methanomicrobia called ANME-1 perform the anaerobic oxidation of methane (AOM) through a process that uses much of the methanogenic pathway. It is unknown whether ANME-1 obligately perform AOM, or whether some of them can perform methanogenesis when methanogenesis is exergonic. Most marine sediments lack advective transport of methane, so AOM occurs in the sulfate methane transition zone (SMTZ) where sulfate-reducing bacteria consume hydrogen produced by fermenters, making hydrogenotrophic methanogenesis exergonic in the reverse direction. When sulfate is depleted deeper in the sediments, hydrogen accumulates making hydrogenotrophic methanogenesis exergonic, and methane accumulates in the methane zone (MZ). In White Oak River estuarine sediments, we found that ANME-1 comprised 99.5% of 16S rRNA genes from amplicons and 100% of 16S rRNA genes from metagenomes of the Methanomicrobia in the SMTZ and 99.9% and 98.3%, respectively, in the MZ. Each of the 16 ANME-1 OTUs (97% similarity) had peaks in the SMTZ that coincided with peaks of putative sulfate-reducing bacteria Desulfatiglans sp. and SEEP-SRB1. In the MZ, ANME-1, but no putative sulfate-reducing bacteria or cultured methanogens, increased with depth. Using publicly available data, we found that ANME-1 was the only group expressing methanogenic genes during both net AOM and net methanogenesis in an enrichment. The commonly-held belief that ANME-1 perform AOM is based on the fact that they dominate natural settings and enrichments where net AOM is measured. We found that ANME-1 also dominate natural settings and enrichment where net methanogenesis is measured, so we conclude that ANME-1 perform methane production. Alternating between AOM and methanogenesis, either in a single ANME-1 cell or between different subclades with similar 16S rRNA sequences of ANME-1, may confer a competitive advantage, explaining the predominance of low-energy adapted ANME-1 in methanogenic sediments worldwide.Abstract ImportanceLife may operate differently at very low energy levels. Natural populations of microbes that make methane survive on some of the lowest energy yields of all life. From all available data, we infer that these microbes alternate between methane production and oxidation, depending on which process is energy-yielding in the environment. This means that much of the methane produced naturally in marine sediments occurs through an organism that is also capable of destroying it under different circumstances.

scholarly journals Fluxes and <sup>13</sup>C isotopic composition of dissolved carbon and pathways of methanogenesis in a fen soil exposed to experimental drought

2008 ◽  
Vol 5 (2) ◽  
pp. 1319-1360 ◽  
Author(s):  
K.-H. Knorr ◽  
B. Glaser ◽  
C. Blodau
Keyword(s):  
Soil Heterogeneity ◽  
Free Energies ◽  
Dissolved Carbon ◽  
Hydrogenotrophic Methanogenesis ◽  
13C Isotope ◽  
Drying And Rewetting ◽  
Labelling Experiment ◽  
Aerobic Soil ◽  
The Impact ◽  
Chamber Measurements

Abstract. The impact of drought and rewetting on carbon cycling in peatland ecosystems is currently debated. We studied the impact of experimental drought and rewetting on intact monoliths from a temperate fen over a period of ~300 days, using a permanently wet treatment and two treatments undergoing drought for 50 days. In one of the mesocosms vegetation had been removed. Net production of CH4 was calculated from mass balances in the peat and emission using static chamber measurements and results compared to 13C isotope budgets of CO2 and CH4 and energy yields of acetoclastic and hydrogenotrophic methanogenesis. Drought retarded methane production after rewetting for days to weeks and promoted methanotrophic activity. Based on isotope and flux budgets, aerobic soil respiration contributed 32–96% in the wet and 86–99% in the other treatments. Drying and rewetting did not shift methanogenic pathways according to δ 13C ratios of CH4 and CO2. Although δ13C ratios indicated a prevalence of hydrogenotrophic methanogenesis, free energies of this process were small and often positive on the horizon scale, suggesting that methane was produced very locally. Fresh plant-derived carbon input apparently supported respiration in the rhizosphere and sustained methanogenesis in the unsaturated zone according to a 13C-CO2 labelling experiment. The study documents that drying and rewetting in a rich fen soil may have little effect on methanogenic pathways but result in rapid shifts between methanogenesis and methanotrophy. Such shifts may be promoted by roots and soil heterogeneity, as hydrogenotrophic methanogenesis occurred locally even when conditions were not conducive for this process in the bulk peat.

scholarly journals Acetate turnover and methanogenic pathways in Amazonian lake sediments

2019 ◽  
Author(s):  
Ralf Conrad ◽  
Melanie Klose ◽  
Alex Enrich-Prast
Keyword(s):  
Lake Sediments ◽  
Turnover Rates ◽  
Hydrogenotrophic Methanogenesis ◽  
Ch4 Production ◽  
Relative Contribution ◽  
Acetate Methyl ◽  
Syntrophic Oxidation ◽  
Aceticlastic Methanogenesis ◽  
Respiratory Index ◽  
Amazonian Lake

Abstract. Lake sediments in Amazonia are a significant source of CH4, a potential greenhouse gas. Previous studies of sediments using 13C analysis found that the contribution of hydrogenotrophic versus aceticlastic methanogenesis to CH4 production was relatively high. Here, we determined the methanogenic pathway in the same sediments (n = 6) by applying [14C]bicarbonate or [2-14C]acetate, and confirmed the high relative contribution (50–80 %) of hydrogenotrophic methanogenesis. The respiratory index (RI) of [2-14C]acetate, which is 14CO2 relative to 14CH4 &amp;plus; 14CO2, divided the sediments into two categories, i.e., those with an RI  0.4 showing that a large percentage of the acetate-methyl was oxidized to CO2 rather than reduced to CH4. Hence, part of the acetate was probably converted to CO2 plus H2 via syntrophic oxidation, thus enhancing hydrogenotrophic methanogenesis. This happened despite the presence of potentially aceticlastic Methanosaetaceae in all the sediments. Alternatively, acetate may have been oxidized with a constituent of the sediment organic matter (humic acid) serving as oxidant. Indeed, apparent acetate turnover rates were larger than CH4 production rates except in those sediments with a R 

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