scholarly journals Understanding the Response of Nitrifying Communities to Disturbance in the McMurdo Dry Valleys, Antarctica

2020 ◽  
Vol 8 (3) ◽  
pp. 404 ◽  
Author(s):  
Maria Monteiro ◽  
Mafalda S. Baptista ◽  
Joana Séneca ◽  
Luís Torgo ◽  
Charles K. Lee ◽  
...  
Keyword(s):  
Functional Groups ◽  
Environmental Conditions ◽  
Organic Matter Content ◽  
Mcmurdo Dry Valleys ◽  
Rrna Gene ◽  
Ammonia Oxidizing Bacteria ◽  
Dry Valleys ◽  
Manipulative Experiment ◽  
Oxidation Rates ◽  
Geochemical Variables

Polar ecosystems are generally limited in nitrogen (N) nutrients, and the patchy availability of N is partly determined by biological pathways, such as nitrification, which are carried out by distinctive prokaryotic functional groups. The activity and diversity of microorganisms are generally strongly influenced by environmental conditions. However, we know little of the attributes that control the distribution and activity of specific microbial functional groups, such as nitrifiers, in extreme cold environments and how they may respond to change. To ascertain relationships between soil geochemistry and the ecology of nitrifying microbial communities, we carried out a laboratory-based manipulative experiment to test the selective effect of key geochemical variables on the activity and abundance of ammonia-oxidizing communities in soils from the McMurdo Dry Valleys of Antarctica. We hypothesized that nitrifying communities, adapted to different environmental conditions within the Dry Valleys, will have distinct responses when submitted to similar geochemical disturbances. In order to test this hypothesis, soils from two geographically distant and geochemically divergent locations, Miers and Beacon Valleys, were incubated over 2 months under increased conductivity, ammonia concentration, copper concentration, and organic matter content. Amplicon sequencing of the 16S rRNA gene and transcripts allowed comparison of the response of ammonia-oxidizing Archaea (AOA) and ammonia-oxidizing Bacteria (AOB) to each treatment over time. This approach was combined with measurements of 15NH4+ oxidation rates using 15N isotopic additions. Our results showed a higher potential for nitrification in Miers Valley, where environmental conditions are milder relative to Beacon Valley. AOA exhibited better adaptability to geochemical changes compared to AOB, particularly to the increase in copper and conductivity. AOA were also the only nitrifying group found in Beacon Valley soils. This laboratorial manipulative experiment provided new knowledge on how nitrifying groups respond to changes on key geochemical variables of Antarctic desert soils, and we believe these results offer new insights on the dynamics of N cycling in these ecosystems.

scholarly journals Low-Dissolved-Oxygen Nitrifying Systems Exploit Ammonia-Oxidizing Bacteria with Unusually High Yields

2011 ◽  
Vol 77 (21) ◽  
pp. 7787-7796 ◽  
Author(s):  
Micol Bellucci ◽  
Irina D. Ofiţeru ◽  
David W. Graham ◽  
Ian M. Head ◽  
Thomas P. Curtis
Keyword(s):  
Wastewater Treatment ◽  
Dissolved Oxygen ◽  
Ammonia Oxidation ◽  
Rrna Gene ◽  
Airflow Rate ◽  
Ammonia Oxidizing Bacteria ◽  
Oxidation Rates ◽  
Operational Costs ◽  
Complete Nitrification ◽  
Low Do

ABSTRACTIn wastewater treatment plants, nitrifying systems are usually operated with elevated levels of aeration to avoid nitrification failures. This approach contributes significantly to operational costs and the carbon footprint of nitrifying wastewater treatment processes. In this study, we tested the effect of aeration rate on nitrification by correlating ammonia oxidation rates with the structure of the ammonia-oxidizing bacterial (AOB) community and AOB abundance in four parallel continuous-flow reactors operated for 43 days. Two of the reactors were supplied with a constant airflow rate of 0.1 liter/min, while in the other two units the airflow rate was fixed at 4 liters/min. Complete nitrification was achieved in all configurations, though the dissolved oxygen (DO) concentration was only 0.5 ± 0.3 mg/liter in the low-aeration units. The data suggest that efficient performance in the low-DO units resulted from elevated AOB levels in the reactors and/or putative development of a mixotrophic AOB community. Denaturing gel electrophoresis and cloning of AOB 16S rRNA gene fragments followed by sequencing revealed that the AOB community in the low-DO systems was a subset of the community in the high-DO systems. However, in both configurations the dominant species belonged to theNitrosomonas oligotrophalineage. Overall, the results demonstrated that complete nitrification can be achieved at low aeration in lab-scale reactors. If these findings could be extended to full-scale plants, it would be possible to minimize the operational costs and greenhouse gas emissions without risk of nitrification failure.

scholarly journals Cold Adapted Nitrosospira sp.: A Potential Crucial Contributor of Ammonia Oxidation in Cryosols of Permafrost-Affected Landscapes in Northeast Siberia

2019 ◽  
Vol 7 (12) ◽  
pp. 699 ◽  
Author(s):  
Tina Sanders ◽  
Claudia Fiencke ◽  
Jennifer Hüpeden ◽  
Eva Maria Pfeiffer ◽  
Eva Spieck
Keyword(s):  
Organic Matter ◽  
Ammonia Oxidation ◽  
Inorganic Nitrogen ◽  
Organic Matter Content ◽  
Matter Content ◽  
Organic Soils ◽  
Ammonia Oxidizing Bacteria ◽  
Cold Adapted ◽  
Oxidation Rates ◽  
North East

Permafrost-affected landscape soils are rich in organic matter and contain a high fraction of organic nitrogen, but much of this organic matter remains inaccessible due to nitrogen limitation. Microbial nitrification is a key process in the nitrogen cycle, controlling the availability of dissolved inorganic nitrogen (DIN) such as ammonium and nitrate. In this study, we investigate the microbial diversity of canonical nitrifiers and their potential nitrifying activity in the active layer of different Arctic cryosols in the Lena River Delta in North-East Siberia. These cryosols are located on Samoylov Island, which has two geomorphological landscapes with mineral soils in the modern floodplain and organic-rich soils in the low-centered polygonal tundra of the Holocene river terrace. Microcosm incubations show that the highest potential ammonia oxidation rates are found in low organic soils, and the rates depend on organic matter content and quality, vegetation cover, and water content. As shown by 16S rRNA amplicon sequencing, nitrifiers represented 0.6% to 6.2% of the total microbial community. More than 50% of the nitrifiers belonged to the genus Nitrosospira. Based on PCR amoA analysis, ammonia-oxidizing bacteria (AOB) were found in nearly all soil types, whereas ammonia-oxidizing archaea (AOA) were only detected in low-organic soils. In cultivation-based approaches, mainly Nitrosospira-like AOB were enriched and characterized as psychrotolerant, with temperature optima slightly above 20 °C. This study suggests a ubiquitous distribution of ammonia-oxidizing microorganisms (bacteria and archaea) in permafrost-affected landscapes of Siberia with cold-adapted AOB, especially of the genus Nitrosospira, as potentially crucial ammonia oxidizers in the cryosols.

Detection and community-level identification of microbial mats in the McMurdo Dry Valleys using drone-based hyperspectral reflectance imaging

2020 ◽  
Vol 32 (5) ◽  
pp. 367-381 ◽  
Author(s):  
Joseph Levy ◽  
S. Craig Cary ◽  
Kurt Joy ◽  
Charles K. Lee
Keyword(s):  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Microbial Mats ◽  
Dynamic Range ◽  
Amplicon Sequencing ◽  
Mcmurdo Dry Valleys ◽  
Rrna Gene ◽  
Sequencing Analysis ◽  
Dry Valleys ◽  
Aircraft System

AbstractThe reflectance spectroscopic characteristics of cyanobacteria-dominated microbial mats in the McMurdo Dry Valleys (MDVs) were measured using a hyperspectral point spectrometer aboard an unmanned aerial system (remotely piloted aircraft system, unmanned aerial vehicle or drone) to determine whether mat presence, type and activity could be mapped at a spatial scale sufficient to characterize inter-annual change. Mats near Howard Glacier and Canada Glacier (ASPA 131) were mapped and mat samples were collected for DNA-based microbiome analysis. Although a broadband spectral parameter (a partial normalized difference vegetation index) identified mats, it missed mats in comparatively deep (> 10 cm) water or on bouldery surfaces where mats occupied fringing moats. A hyperspectral parameter (B6) did not have these shortcomings and recorded a larger dynamic range at both sites. When linked with colour orthomosaic data, B6 band strength is shown to be capable of characterizing the presence, type and activity of cyanobacteria-dominated mats in and around MDV streams. 16S rRNA gene polymerase chain reaction amplicon sequencing analysis of the mat samples revealed that dominant cyanobacterial taxa differed between spectrally distinguishable mats, indicating that spectral differences reflect underlying biological distinctiveness. Combined rapid-repeat hyperspectral measurements can be applied in order to monitor the distribution and activity of sentinel microbial ecosystems across the terrestrial Antarctic.

scholarly journals The lithic microbial ecosystems of Antarctica’s McMurdo Dry Valleys

2014 ◽  
Vol 26 (5) ◽  
pp. 459-477 ◽  
Author(s):  
Asunción De Los Ríos ◽  
Jacek Wierzchos ◽  
Carmen Ascaso
Keyword(s):  
Environmental Conditions ◽  
Extracellular Polymeric Substances ◽  
Heterotrophic Bacteria ◽  
Community Organization ◽  
Mcmurdo Dry Valleys ◽  
Microbial Consortia ◽  
Dry Valleys ◽  
Microbial Life ◽  
Environmental Controls ◽  
Microbial Ecosystems

AbstractWe review the lithic microbial ecosystems of the McMurdo Dry Valleys as the main form of terrestrial colonization in this region, and assess the role of environmental controls such as temperature, solar radiation, water availability, wind, nutrient availability, salinity and the physicochemical properties of the colonized rock. Epilithic communities, especially those dominated by lichens, are able to withstand extreme environmental conditions but subsurface endolithic microhabitats provide more tolerant conditions. Endolithic microbial communities can be grouped into two main classes: eukaryotic communities (dominated by lichenized fungi and algae) and prokaryotic communities (dominated by cyanobacteria). Heterotrophic bacteria and non-lichenized algae and fungi (mainly black fungi) are also components of these communities. These lithobiontic microorganisms generally have effective mechanisms against freezing temperatures and desiccation. Extracellular polymeric substances play an important role not only in protecting microbial cells but also in community organization and in mitigating microenvironmental conditions. Antarctic lithobiontic communities are comprised of microbial consortia within which multiple interactions between the different biological and abiotic components are essential for microbial survival, whilst fossils and biomarkers provide evidence of earlier successful microbial life in Antarctic deserts. Finally, the uniqueness of the present lithobiont assemblages suggests they are the outcome of geographical isolation during the evolution of the continent and not merely the descendants of a subset of globally distributed taxa that have adapted to the extreme environmental conditions.

Cryostratigraphy of mid-Miocene permafrost at Friis Hills, McMurdo Dry Valleys of Antarctica

2020 ◽  
pp. 1-15
Author(s):  
Marjolaine Verret ◽  
Warren Dickinson ◽  
Denis Lacelle ◽  
David Fisher ◽  
Kevin Norton ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Meteoric Water ◽  
Arid Environment ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Ground Ice ◽  
Near Surface ◽  
Air Temperatures ◽  
Drilling Project

Abstract The origin and stability of ground ice in the stable uplands of the McMurdo Dry Valleys remains poorly understood, with most studies focusing on the near-surface permafrost. The 2016 Friis Hills Drilling Project retrieved five cores reaching 50 m depth in mid-Miocene permafrost, a period when Antarctica transitioned to a hyper-arid environment. This study characterizes the cryostratigraphy of arguably the oldest permafrost on Earth and assesses 15 Myr of ground ice evolution using the REGO model. Four cryostratigraphic units were identified: 1) surficial dry permafrost (0–30 cm), 2) ice-rich to ice-poor permafrost (0.3–5.0 m) with high solute load and δ18O values (-16.2 ± 1.8‰) and low D-excess values (-65.6 ± 4.3‰), 3) near-dry permafrost (5–20 m) and 4) ice-poor to ice-rich permafrost (20–50 m) containing ice lenses with low solute load and δ18O values (-34.6 ± 1.2‰) and D-excess of 6.9 ± 2.6‰. The near-surface δ18O profile of ground ice is comparable to other sites in the stable uplands, suggesting that this ice is actively responding to changing surface environmental conditions and challenging the assumption that the surface has remained frozen for 13.8 Myr. The deep ice lenses probably originate from the freezing of meteoric water during the mid-Miocene, and their δ18O composition suggests mean annual air temperatures ~7–11°C warmer than today.

THE IMPACT OF CLIMATE CHANGE ON LAKE VANDA, MCMURDO DRY VALLEYS, ANTARCTICA

2016 ◽  
Author(s):  
Devin Castendyk ◽  
◽  
Maciej K. Obryk ◽  
Sasha Z. Leidman ◽  
Michael Gooseff ◽  
...  
Keyword(s):  
Climate Change ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Impact Of Climate Change ◽  
The Impact

PRELIMINARY CHARACTERIZATION OF WIND-BLOWN DUST FROM THE MCMURDO DRY VALLEYS OF ANTARCTICA

2016 ◽  
Author(s):  
Melisa A. Diaz ◽  
◽  
Susan A. Welch ◽  
Kathleen A. Welch ◽  
Alia L. Khan ◽  
...  
Keyword(s):  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Preliminary Characterization

ALPINE GLACIER ADVANCE DURING MIS 11 IN THE MCMURDO DRY VALLEYS, ANTARCTICA

2016 ◽  
Author(s):  
Kate M. Swanger ◽  
◽  
Joerg M. Schaefer ◽  
Gisela Winckler
Keyword(s):  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Alpine Glacier ◽  
Glacier Advance

SOLUBLE AND BULK GEOCHEMICAL ANALYSIS OF AEOLIAN MATERIAL FROM THE MCMURDO DRY VALLEYS, ANTARCTICA

2017 ◽  
Author(s):  
Melisa A. Diaz ◽  
◽  
Byron J. Adams ◽  
Alia L. Khan ◽  
Kathleen A. Welch ◽  
...  
Keyword(s):  
Mcmurdo Dry Valleys ◽  
Geochemical Analysis ◽  
Dry Valleys
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