scholarly journals Biogeochemical evidence of anaerobic methane oxidation and anaerobic ammonium oxidation in a stratified lake using stable isotopes

2020 ◽  
Vol 17 (20) ◽  
pp. 5149-5161
Author(s):  
Florian Einsiedl ◽  
Anja Wunderlich ◽  
Mathieu Sebilo ◽  
Ömer K. Coskun ◽  
William D. Orsi ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Methane Oxidation ◽  
Water Depth ◽  
Methane Concentration ◽  
Methane Emissions ◽  
Freshwater Ecosystems ◽  
Anaerobic Methane Oxidation ◽  
Ammonium Oxidation ◽  
Anaerobic Oxidation ◽  
Oxidation Of Methane

Abstract. Nitrate pollution of freshwaters and methane emissions into the atmosphere are crucial factors in deteriorating the quality of drinking water and in contributing to global climate change. The n-damo (nitrite-dependent anaerobic methane oxidation), nitrate-dependent anaerobic methane oxidation and the anaerobic oxidation of ammonium (anammox) represent two microbially mediated processes that can reduce nitrogen loading of aquatic ecosystems and associated methane emissions to the atmosphere. Here, we report vertical concentration and stable-isotope profiles of CH4, NO3-, NO2-, and NH4+ in the water column of Fohnsee (lake in southern Bavaria, Germany) that may indicate linkages between denitrification, anaerobic oxidation of methane (AOM), and anammox. At a water depth from 12 to 20 m, a methane–nitrate transition zone (NMTZ) was observed, where δ13C values of methane and δ15N and δ18O of dissolved nitrate markedly increased in concert with decreasing concentrations of methane and nitrate. These data patterns, together with the results of a simple 1-D diffusion model linked with a degradation term, show that the nonlinear methane concentration profile cannot be explained by diffusion and that microbial oxidation of methane coupled with denitrification under anaerobic conditions is the most parsimonious explanation for these data trends. In the methane zone at the bottom of the NMTZ (20 to 22 m) δ15N of ammonium increased by 4 ‰, while ammonium concentrations decreased. In addition, a strong 15N enrichment of dissolved nitrate was observed at a water depth of 20 m, suggesting that anammox is occurring together with denitrification. The conversion of nitrite to N2 and nitrate during anammox is associated with an inverse N isotope fractionation and may explain the observed increasing offset (Δδ15N) of 26 ‰ between δ15N values of dissolved nitrate and nitrite at a water depth of 20 m compared to the Δδ15Nnitrate-nitrite of 11 ‰ obtained in the NMTZ at a water depth between 16 and 18 m. The associated methane concentration and stable-isotope profiles indicate that some of the denitrification may be coupled to AOM, an observation supported by an increased concentration of bacteria known to be involved in n-damo/denitrification with AOM (NC10 and Crenothrix) and anammox (“Candidatus Anammoximicrobium”) whose concentrations were highest in the methane and ammonium oxidation zones, respectively. This study shows the potential for a coupling of microbially mediated nitrate-dependent methane oxidation with anammox in stratified freshwater ecosystems, which may be important for affecting both methane emissions and nitrogen concentrations in lakes.

scholarly journals Biogeochemical evidence of anaerobic methane oxidation and anaerobic ammonium oxidation in a stratified lake using stable isotopes

2020 ◽  
Author(s):  
Florian Einsiedl ◽  
Anja Wunderlich ◽  
Mathieu Sebilo ◽  
Ömer K. Coskun ◽  
William D. Orsi ◽  
...  
Keyword(s):  
Methane Oxidation ◽  
Water Depth ◽  
Methane Emissions ◽  
Nitrogen Loading ◽  
Anaerobic Methane Oxidation ◽  
Anaerobic Oxidation Of Methane ◽  
Ammonium Oxidation ◽  
Anaerobic Oxidation ◽  
Stratified Lake ◽  
Oxidation Of Methane

Abstract. Nitrate pollution of freshwaters and methane emissions into the atmosphere are crucial factors in deteriorating the quality of drinking water and in contributing to global climate change. The nitrate dependent anaerobic methane oxidation and the anaerobic oxidation of ammonium (anammox) have the potential to reduce nitrogen loading of aquatic ecosystems and to reduce methane emissions to the atmosphere. Here, we report vertical concentration profiles and corresponding stable isotope compositions of CH4, NO3−, NO2− and NH4+ in the water column of a stratified lake, which suggest linkages between anaerobic oxidation of methane (AOM), denitrification, and anammox. In a water depth from 12 to 20 m, a methane-nitrate transition zone (NMTZ) was observed, where δ13C values of methane and δ15N and δ18O of dissolved nitrate markedly increased in concert with decreasing concentrations of methane and nitrate. These data patterns, together with a simple 1D diffusion model show that the non-linear methane concentration profile cannot be explained by diffusion or micro-aerobic methane oxidation, and that microbial oxidation of methane coupled with denitrification under anaerobic conditions is the most likely explanation for these data trends. In the methane zone at the bottom of the NMTZ (20 m to 22 m) δ15N of ammonium increased by 4 ‰, while ammonium concentrations decreased. In addition, a strong 15N enrichment of dissolved nitrate was observed at a water depth of 20 m, suggesting that anammox is occuring together with denitrification coupled to AOM. The conversion of nitrite to N2 and nitrate during anammox is namely associated with an inverse N isotope fractionation and may explain the observed increasing offset (Δδ15N) of 26 ‰ between δ15N values of dissolved nitrate and nitrite at a water depth of 20 m compared to the Δδ15Nnitrate-nitrite of 11 ‰ obtained in the NMTZ between a water depth of 16 m and 18 m. The geochemcical zones were found to contain significantly different microbial communities that consist of bacteria known to be involved in denitrification with AOM (Crenothrix and NC10), and anammox (Candidatus Anammoximicrobium), confirming the presence of microbial groups potentially responsible for the proposed linkages between AOM, denitrification, and anammox. This study gives insights into the yet overlooked AOM-denitrification-anammox process in stratified lakes that can regulate methane emisssions from and nitrogen concentrations in lakes.

scholarly journals Anaerobic oxidation of methane in grassland soils used for cattle husbandry

2012 ◽  
Vol 9 (4) ◽  
pp. 4919-4945
Author(s):  
A. Bannert ◽  
C. Bogen ◽  
J. Esperschütz ◽  
A. Koubová ◽  
F. Buegger ◽  
...  
Keyword(s):  
Methane Oxidation ◽  
Anaerobic Methane Oxidation ◽  
Anaerobic Oxidation Of Methane ◽  
Type I ◽  
Anaerobic Oxidation ◽  
Nutrient Source ◽  
Oxidation Activity ◽  
Oxidation Of Methane ◽  
Cattle Husbandry

Abstract. While the importance of anaerobic methane oxidation has been reported for marine ecosystems, the role of this process in soils is still questionable. Grasslands used as pastures for cattle-overwintering show an increase in anaerobic soil micro-sites caused by animal treading and excrement deposition. Therefore anaerobic potential methane oxidation activity of severely impacted soil from a cattle winter pasture was investigated in an incubation experiment under anaerobic conditions using 13C-labeled methane. We were able to detect a high microbial activity utilizing CH4 as nutrient source shown by the respiration of 13CO2. Measurements of possible terminal electron acceptors for anaerobic oxidation of methane were carried out. Soil sulfate concentrations were too low to explain the oxidation of the amount of methane added, but enough nitrate and iron(III) were detected. However, only nitrate was consumed during the experiment. 13C-PLFA analyses clearly showed the utilization of CH4 as nutrient source mainly by organisms harbouring 16:1ω7 PLFAs. These lipids were found in Gram-negative microorganisms and anaerobes. The fact that these lipids are also typical for type I methanotrophs, known as aerobic methane oxidizers, might indicate a link between aerobic and anaerobic methane oxidation.

scholarly journals Microbial Diversity of Hydrothermal Sediments in the Guaymas Basin: Evidence for Anaerobic Methanotrophic Communities

2002 ◽  
Vol 68 (4) ◽  
pp. 1994-2007 ◽  
Author(s):  
Andreas Teske ◽  
Kai-Uwe Hinrichs ◽  
Virginia Edgcomb ◽  
Alvin de Vera Gomez ◽  
David Kysela ◽  
...  
Keyword(s):  
16S Rrna ◽  
Methane Oxidation ◽  
Gulf Of California ◽  
Trophic Ecology ◽  
Anaerobic Methane Oxidation ◽  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
Bacterial Populations ◽  
Guaymas Basin ◽  
Oxidation Of Methane

ABSTRACT Microbial communities in hydrothermally active sediments of the Guaymas Basin (Gulf of California, Mexico) were studied by using 16S rRNA sequencing and carbon isotopic analysis of archaeal and bacterial lipids. The Guaymas sediments harbored uncultured euryarchaeota of two distinct phylogenetic lineages within the anaerobic methane oxidation 1 (ANME-1) group, ANME-1a and ANME-1b, and of the ANME-2c lineage within the Methanosarcinales, both previously assigned to the methanotrophic archaea. The archaeal lipids in the Guaymas Basin sediments included archaeol, diagnostic for nonthermophilic euryarchaeota, and sn-2-hydroxyarchaeol, with the latter compound being particularly abundant in cultured members of the Methanosarcinales. The concentrations of these compounds were among the highest observed so far in studies of methane seep environments. The δ-13C values of these lipids (δ-13C = −89 to −58‰) indicate an origin from anaerobic methanotrophic archaea. This molecular-isotopic signature was found not only in samples that yielded predominantly ANME-2 clones but also in samples that yielded exclusively ANME-1 clones. ANME-1 archaea therefore remain strong candidates for mediation of the anaerobic oxidation of methane. Based on 16S rRNA data, the Guaymas sediments harbor phylogenetically diverse bacterial populations, which show considerable overlap with bacterial populations of geothermal habitats and natural or anthropogenic hydrocarbon-rich sites. Consistent with earlier observations, our combined evidence from bacterial phylogeny and molecular-isotopic data indicates an important role of some novel deeply branching bacteria in anaerobic methanotrophy. Anaerobic methane oxidation likely represents a significant and widely occurring process in the trophic ecology of methane-rich hydrothermal vents. This study stresses a high diversity among communities capable of anaerobic oxidation of methane.

scholarly journals Anaerobic oxidation of methane in grassland soils used for cattle husbandry

2012 ◽  
Vol 9 (10) ◽  
pp. 3891-3899 ◽  
Author(s):  
A. Bannert ◽  
C. Bogen ◽  
J. Esperschütz ◽  
A. Koubová ◽  
F. Buegger ◽  
...  
Keyword(s):  
Methane Oxidation ◽  
Enrichment Culture ◽  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
Incubation Experiment ◽  
Nutrient Source ◽  
Oxidation Activity ◽  
Oxidation Of Methane ◽  
Cattle Husbandry

Abstract. While the importance of anaerobic methane oxidation has been reported for marine ecosystems, the role of this process in soils is still questionable. Grasslands used as pastures for cattle overwintering show an increase in anaerobic soil micro-sites caused by animal treading and excrement deposition. Therefore, anaerobic potential methane oxidation activity of severely impacted soil from a cattle winter pasture was investigated in an incubation experiment under anaerobic conditions using 13C-labelled methane. We were able to detect a high microbial activity utilizing CH4 as nutrient source shown by the respiration of 13CO2. Measurements of possible terminal electron acceptors for anaerobic oxidation of methane were carried out. Soil sulfate concentrations were too low to explain the oxidation of the amount of methane added, but enough nitrate and iron(III) were detected. However, only nitrate was consumed during the experiment. 13C-PLFA analyses clearly showed the utilization of CH4 as nutrient source mainly by organisms harbouring 16:1ω7 PLFAs. These lipids were also found as most 13C-enriched fatty acids by Raghoebarsing et al. (2006) after addition of 13CH4 to an enrichment culture coupling denitrification of nitrate to anaerobic oxidation of methane. This might be an indication for anaerobic oxidation of methane by relatives of "Candidatus Methylomirabilis oxyfera" in the investigated grassland soil under the conditions of the incubation experiment.

scholarly journals High rates of anaerobic methane oxidation in freshwater wetlands reduce potential atmospheric methane emissions

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
K. E. A. Segarra ◽  
F. Schubotz ◽  
V. Samarkin ◽  
M. Y. Yoshinaga ◽  
K-U Hinrichs ◽  
...  
Keyword(s):  
Methane Oxidation ◽  
Methane Emissions ◽  
Freshwater Wetlands ◽  
Anaerobic Methane Oxidation ◽  
Atmospheric Methane

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

2011 ◽  
Vol 77 (13) ◽  
pp. 4429-4436 ◽  
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.

A new intra-aerobic metabolism in the nitrite-dependent anaerobic methane-oxidizing bacterium Candidatus ‘Methylomirabilis oxyfera’

2011 ◽  
Vol 39 (1) ◽  
pp. 243-248 ◽  
Author(s):  
Ming L. Wu ◽  
Katharina F. Ettwig ◽  
Mike S.M. Jetten ◽  
Marc Strous ◽  
Jan T. Keltjens ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Methane Oxidation ◽  
Current Knowledge ◽  
Methanogenic Archaea ◽  
Anaerobic Methane Oxidation ◽  
Oxidation Pathway ◽  
Sulfate Reducing ◽  
Oxidation Of Methane ◽  
Aerobic Methanotrophs ◽  
Reverse Methanogenesis

Biological methane oxidation proceeds either through aerobic or anaerobic pathways. The newly discovered bacterium Candidatus ‘Methylomirabilis oxyfera’ challenges this dichotomy. This bacterium performs anaerobic methane oxidation coupled to denitrification, but does so in a peculiar way. Instead of scavenging oxygen from the environment, like the aerobic methanotrophs, or driving methane oxidation by reverse methanogenesis, like the methanogenic archaea in sulfate-reducing systems, it produces its own supply of oxygen by metabolizing nitrite via nitric oxide into oxygen and dinitrogen gas. The intracellularly produced oxygen is then used for the oxidation of methane by the classical aerobic methane oxidation pathway involving methane mono-oxygenase. The present mini-review summarizes the current knowledge about this process and the micro-organism responsible for it.

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