Nitrate-dependent anaerobic methane oxidation and chemolithotrophic denitrification in a temperate eutrophic lake

Abstract While the emissions of methane (CH4) by the natural systems have been widely investigated, the aquatic sinks are still poorly constrained. Here, we investigated CH4 cycle and its interactions with nitrogen (N), iron (Fe) and manganese (Mn) cycles in the oxic-anoxic interface and deep anoxic waters of a small, meromictic and eutrophic lake, during two summertime sampling campaigns. Anaerobic CH4 oxidation (AOM) was measured from the temporal decrease of CH4 concentrations, with addition of 3 potential electron acceptors (NO3–, iron oxides (Fe(OH)3) and manganese oxides (MnO2)). Experiments with addition of either 15N-labeled nitrate (15N-NO3–) or 15N-NO3– combined with sulfide (H2S), to measure denitrification, chemolithotrophic denitrification and anaerobic ammonium oxidation (anammox) rates were also performed. Measurements showed AOM rates up to 3.8 µmol CH4 L–1 d–1 that strongly increased with the addition of NO3– and moderately increased with the addition of Fe(OH)3. No stimulation was observed with MnO2 added. Potential denitrification and anammox rates up to 63 and 0.27 µmol N2 L–1 d–1, respectively, were measured when only 15N-NO3– was added. When H2S was added, both denitrification and anammox rates increased. Altogether, these results suggest that prokaryote communities in the redoxcline are able to efficiently use the most available substrates.

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Modification of methane oxidation pathways during long-term incubations of methanic lake sediments

10.5194/bg-2021-223 ◽

2021 ◽

Author(s):

Hanni Vigderovich ◽

Werner Eckert ◽

Michal Elul ◽

Maxim Rubin-Blum ◽

Marcus Elvert ◽

...

Keyword(s):

Lake Sediments ◽

Carbon Isotope ◽

Iron Oxides ◽

Methane Oxidation ◽

Electron Acceptors ◽

Anaerobic Oxidation Of Methane ◽

Methanotrophic Bacteria ◽

Oxidation Of Methane ◽

Isotope Measurements

Abstract. Anaerobic oxidation of methane (AOM) is one of the major processes limiting the release of the greenhouse gas methane from natural environments. In Lake Kinneret sediments, iron-coupled AOM (Fe-AOM) was suggested to play a substantial role (10–15 % relative to methanogenesis) in the methanic zone (> 20 cm sediment depth), based on geochemical profiles and experiments on fresh sediments. Apparently, the oxidation of methane is mediated by a combination of mcr gene bearing archaea and aerobic bacterial methanotrophs. Here we aimed to investigate the survival of this complex microbial interplay under controlled conditions. We followed the AOM process during long-term (~18 months) anaerobic slurry experiments of these methanic sediments with two stages of incubations and additions of 13C-labeled methane, multiple electron acceptors and inhibitors. After these incubation stages carbon isotope measurements in the dissolved inorganic pool still showed considerable AOM (3–8 % relative to methanogenesis). Specific lipid carbon isotope measurements and metagenomic analyses indicate that after the prolonged incubation aerobic methanotrophic bacteria were no longer involved in the oxidation process, whereas mcr gene bearing archaea were most likely responsible for oxidizing the methane. Humic substances and iron oxides are likely electron acceptors to support this oxidation, whereas sulfate, manganese, nitrate, and nitrite did not support the AOM in these methanic sediments. Our results suggest in the natural lake sediments methanotrophic bacteria are responsible for part of the methane oxidation by the reduction of combined micro levels of oxygen and iron oxides in a cryptic cycle, while the rest of the methane is converted by reverse methanogenesis. After long-term incubation, the latter prevails without bacterial methanotropic activity and with a different iron reduction pathway.

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Rates and pathways of CH<sub>4</sub> oxidation in ferruginous Lake Matano, Indonesia

10.5194/bg-2015-533 ◽

2016 ◽

Cited By ~ 2

Author(s):

A. Sturm ◽

D. A. Fowle ◽

C. Jones ◽

K. Leslie ◽

S. Nomosatryo ◽

...

Keyword(s):

Carbon Dioxide ◽

Energy Source ◽

Methane Oxidation ◽

Ch4 Oxidation ◽

Apparent Absence ◽

Oxidation Rates ◽

Lake Matano ◽

Anoxic Waters ◽

Carbon Dioxide Co2 ◽

Tracer Experiments

Abstract. This study evaluates rates and pathways of methane (CH4) oxidation and uptake using 14C-based tracer experiments throughout the oxic and anoxic waters of ferruginous Lake Matano. Methane oxidation rates in Lake Matano are low compared to other lakes, but are sufficiently high to preclude strong CH4 fluxes to the atmosphere. In addition to aerobic CH4 oxidation, which takes place in Lake Matano's oxic mixolimnion, we also detected CH4 oxidation in Lake Matano's anoxic ferruginous waters. Here, CH4 oxidation proceeds in the apparent absence of oxygen (O2) and instead appears to be coupled to nitrate (NO3−), nitrite (NO2−), iron (Fe), or manganese (Mn) reduction. Throughout the lake, the fraction of CH4 carbon that is assimilated vs. oxidized to carbon dioxide (CO2) is high, indicating extensive CH4 conversion to biomass and underscoring the importance of CH4 as a carbon and energy source in Lake Matano and potentially other ferruginous or low productivity environments.

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Methane oxidation in the waters of a humic-rich boreal lake stimulated by photosynthesis, nitrite, Fe(III) and humics

Biogeosciences ◽

10.5194/bg-18-3087-2021 ◽

2021 ◽

Vol 18 (10) ◽

pp. 3087-3101

Author(s):

Sigrid van Grinsven ◽

Kirsten Oswald ◽

Bernhard Wehrli ◽

Corinne Jegge ◽

Jakob Zopfi ◽

...

Keyword(s):

Water Column ◽

Methane Oxidation ◽

Water Concentration ◽

Eutrophic Lake ◽

Boreal Lakes ◽

Ch4 Oxidation ◽

Anoxic Water ◽

Ch4 Emissions ◽

Oxidation Rates ◽

Incubation Experiments

Abstract. Small boreal lakes are known to contribute significantly to global CH4 emissions. Lake Lovojärvi is a eutrophic lake in southern Finland with bottom water CH4 concentrations up to 2 mM. However, the surface water concentration, and thus the diffusive emission potential, was low (< 0.5 µM). We studied the biogeochemical processes involved in CH4 removal by chemical profiling and through incubation experiments. δ13C-CH4 profiling of the water column revealed a methane-oxidation hotspot just below the oxycline and zones of CH4 oxidation within the anoxic water column. In incubation experiments involving the addition of light and/or oxygen, CH4 oxidation rates in the anoxic hypolimnion were enhanced 3-fold, suggesting a major role for photosynthetically fueled aerobic CH4 oxidation. We observed a distinct peak in CH4 concentration at the chlorophyll-a maximum, caused by either in situ CH4 production or other CH4 inputs such as lateral transport from the littoral zone. In the dark anoxic water column at 7 m depth, nitrite seemed to be the key electron acceptor involved in CH4 oxidation, yet additions of Fe(III), anthraquinone-2,6-disulfonate and humic substances also stimulated anoxic CH4 oxidation. Surprisingly, nitrite seemed to inhibit CH4 oxidation at all other depths. Overall, this study shows that photosynthetically fueled CH4 oxidation can be a key process in CH4 removal in the water column of humic, turbid lakes, thereby limiting diffusive CH4 emissions from boreal lakes. Yet, it also highlights the potential importance of a whole suite of alternative electron acceptors, including humics, in these freshwater environments in the absence of light and oxygen.

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Anaerobic methane oxidation in an East African great lake (Lake Kivu)

10.5194/bg-2016-300 ◽

2016 ◽

Cited By ~ 5

Author(s):

Fleur A. E. Roland ◽

François Darchambeau ◽

Cédric Morana ◽

Sean A. Crowe ◽

Bo Thamdrup ◽

...

Keyword(s):

Methane Oxidation ◽

Anaerobic Methane Oxidation ◽

Ch4 Oxidation ◽

Oxidation Rates ◽

Anoxic Waters ◽

Nitrate Consumption ◽

Lake Kivu ◽

Consumption Rates ◽

Field Campaigns ◽

Aerobic And Anaerobic

Abstract. This study investigates methane (CH4) oxidation in the water column of Lake Kivu, a deep meromictic tropical lake containing large quantities of CH4 in the anoxic deep waters. Depth profiles of dissolved gases (CH4 and nitrous oxide (N2O)) and of the different potential electron acceptors for anaerobic methane oxidation (AOM) (nitrate, sulfate, iron and manganese) were determined during six field campaigns between June 2011 and August 2014. Bacterial abundance all along the vertical profiles was also determined by flow cytometry during three field campaigns, and denitrification measurements based on stable isotopes were performed twice. Incubation experiments were performed to quantify CH4 oxidation and nitrate consumption rates, with a focus on AOM, without and with an inhibitor of sulfate-reducing bacteria activity (molybdate). Nitrate consumption rates were measured in these incubations. Substantial CH4 oxidation activity was observed in oxic and anoxic waters, and in the upper anoxic waters of Lake Kivu, CH4 is a major electron donor to sustain anaerobic metabolic processes coupled to AOM. The maximum aerobic and anaerobic CH4 oxidation rates were estimated to 27 ± 2 and 16 ± 8 µmol L−1 d−1, respectively. We observed a decrease of AOM rates when molybdate was added for half of the measurements, strongly suggesting the occurrence of AOM linked to sulfate reduction, but an increase of AOM rates was observed for the other half. Nitrate reduction rates and dissolved manganese production rates tended to be higher with the addition of molybdate, but the maximum rates of 0.6 ± 0.02 and 11 ± 2 µmol L−1 d−1, respectively, were never high enough to explain AOM rates observed at the same depths. We also put in evidence a difference in relative importance of aerobic and anaerobic CH4 oxidation between the seasons, with a higher importance of aerobic oxidation when the oxygenated layer was thicker (in dry season).

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Nitrogen isotope effects can be used to diagnose N transformations in wastewater anammox systems

Scientific Reports ◽

10.1038/s41598-021-87184-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Paul M. Magyar ◽

Damian Hausherr ◽

Robert Niederdorfer ◽

Nicolas Stöcklin ◽

Jing Wei ◽

...

Keyword(s):

Isotope Effect ◽

Isotope Composition ◽

Isotope Effects ◽

Nitrogen Isotope ◽

Anammox Bacteria ◽

Ammonium Oxidation ◽

Experimental Conditions ◽

N Transformations ◽

Natural Systems ◽

Inverse Isotope Effect

AbstractAnaerobic ammonium oxidation (anammox) plays an important role in aquatic systems as a sink of bioavailable nitrogen (N), and in engineered processes by removing ammonium from wastewater. The isotope effects anammox imparts in the N isotope signatures (15N/14N) of ammonium, nitrite, and nitrate can be used to estimate its role in environmental settings, to describe physiological and ecological variations in the anammox process, and possibly to optimize anammox-based wastewater treatment. We measured the stable N-isotope composition of ammonium, nitrite, and nitrate in wastewater cultivations of anammox bacteria. We find that the N isotope enrichment factor 15ε for the reduction of nitrite to N2 is consistent across all experimental conditions (13.5‰ ± 3.7‰), suggesting it reflects the composition of the anammox bacteria community. Values of 15ε for the oxidation of nitrite to nitrate (inverse isotope effect, − 16 to − 43‰) and for the reduction of ammonium to N2 (normal isotope effect, 19–32‰) are more variable, and likely controlled by experimental conditions. We argue that the variations in the isotope effects can be tied to the metabolism and physiology of anammox bacteria, and that the broad range of isotope effects observed for anammox introduces complications for analyzing N-isotope mass balances in natural systems.

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Chromium(iii) oxidation by biogenic manganese oxides with varying structural ripening

Environmental Science Processes & Impacts ◽

10.1039/c4em00077c ◽

2014 ◽

Vol 16 (9) ◽

pp. 2127-2136 ◽

Cited By ~ 33

Author(s):

Yuanzhi Tang ◽

Samuel M. Webb ◽

Emily R. Estes ◽

Colleen M. Hansel

Keyword(s):

Environmental Conditions ◽

Manganese Oxides ◽

Natural Systems ◽

Mn Oxides

Manganese (Mn) oxides, which are generally considered biogenic in origin within natural systems, are the only oxidants of Cr(iii) under typical environmental conditions.

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Methane oxidation and methane fluxes in the ocean surface layer and deep anoxic waters

Nature ◽

10.1038/327226a0 ◽

1987 ◽

Vol 327 (6119) ◽

pp. 226-229 ◽

Cited By ~ 168

Author(s):

B. B. Ward ◽

K. A. Kilpatrick ◽

P. C. Novelli ◽

M. I. Scranton

Keyword(s):

Surface Layer ◽

Methane Oxidation ◽

Ocean Surface ◽

Anoxic Waters ◽

Methane Fluxes ◽

Ocean Surface Layer

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In situ CH4 oxidation inhibition and 13CH4 labeling reveal methane oxidation and emission patterns in a subarctic heath ecosystem

Biogeochemistry ◽

10.1007/s10533-018-0441-2 ◽

2018 ◽

Vol 138 (2) ◽

pp. 197-213 ◽

Cited By ~ 3

Author(s):

Emily Pickering Pedersen ◽

Anders Michelsen ◽

Bo Elberling

Keyword(s):

Methane Oxidation ◽

Ch4 Oxidation

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Anaerobic Oxidation of Methane in Sediments of Lake Constance, an Oligotrophic Freshwater Lake

Applied and Environmental Microbiology ◽

10.1128/aem.00340-11 ◽

2011 ◽

Vol 77 (13) ◽

pp. 4429-4436 ◽

Cited By ~ 141

Author(s):

Jörg S. Deutzmann ◽

Bernhard Schink

Keyword(s):

Methane Oxidation ◽

Electron Acceptors ◽

Molecular Techniques ◽

Freshwater Lake ◽

Lake Constance ◽

Anaerobic Oxidation Of Methane ◽

Anaerobic Oxidation ◽

Terminal Electron Acceptor ◽

Oxidation Of Methane ◽

Freshwater Habitats

ABSTRACTAnaerobic oxidation of methane (AOM) with sulfate as terminal electron acceptor has been reported for various environments, including freshwater habitats, and also, nitrate and nitrite were recently shown to act as electron acceptors for methane oxidation in eutrophic freshwater habitats. Radiotracer experiments with sediment material of Lake Constance, an oligotrophic freshwater lake, were performed to follow14CO2formation from14CH4in sediment incubations in the presence of different electron acceptors, namely, nitrate, nitrite, sulfate, or oxygen. Whereas14CO2formation without and with sulfate addition was negligible, addition of nitrate increased14CO2formation significantly, suggesting that AOM could be coupled to denitrification. Nonetheless, denitrification-dependent AOM rates remained at least 1 order of magnitude lower than rates of aerobic methane oxidation. Using molecular techniques, putative denitrifying methanotrophs belonging to the NC10 phylum were detected on the basis of thepmoAand 16S rRNA gene sequences. These findings show that sulfate-dependent AOM was insignificant in Lake constant sediments. However, AOM can also be coupled to denitrification in this oligotrophic freshwater habitat, providing first indications that this might be a widespread process that plays an important role in mitigating methane emissions.

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