News

Anammox bacteria generate energy from wastewater while taking a breath

"A type of anaerobic bacteria responsible for more than 50 percent of nitrogen loss from marine environments has been shown to use solid-state matter present outside their cells for respiration. The finding by KAUST researchers adds to knowledge of the global nitrogen cycle and has important energy-saving potential for wastewater treatment. [...]"

Source: Phys.org

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Warming stimulates sediment denitrification at the expense of anaerobic ammonium oxidation

Abstract.

"Temperature is one of the fundamental environmental variables governing microbially mediated denitrification and anaerobic ammonium oxidation (anammox) in sediments. The GHG nitrous oxide (N2O) is produced during denitrification, but not by anammox, and knowledge of how these pathways respond to global warming remains limited. [...]"

Source: Nature Climate Change
Authors: Ehui Tan et al.
DOI: 10.1038/s41558-020-0723-2

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Interactions of anaerobic ammonium oxidizers and sulfide-oxidizing bacteria in a substrate-limited model system mimicking the marine environment

Abstract. 

"In nature anaerobic ammonium oxidation (anammox) and denitrification processes convert fixed nitrogen to gaseous nitrogen compounds, which are then released to the atmosphere. While anammox bacteria produce N2 from ammonium and nitrite, in the denitrification process nitrate and nitrite are converted to N2 and the greenhouse gas nitrous oxide (N2O). [...]"

Source: FEMS Microbiology Ecology
Authors: Lina Russ et al. 
DOI: 10.1093/femsec/fiz137

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Environmental controls on bacteriohopanepolyol profiles of benthic microbial mats from Lake Fryxell, Antarctica

Abstract.

"Bacteriohopanepolyols (BHPs) are pentacyclic triterpenoid lipids that contribute to the structural integrity and physiology of some bacteria. Because some BHPs originate from specific classes of bacteria, BHPs have potential as taxonomically and environmentally diagnostic biomarkers. For example, a stereoisomer of bacteriohopanetetrol (informally BHT II) has been associated with anaerobic ammonium oxidation (anammox) bacteria and suboxic to anoxic marine environments where anammox is active. [...]"

Source: geobiology
Authors: Emily D. Matys et al.
DOI: 10.1111/gbi.12353

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Dual nitrogen and oxygen isotope fractionation during anaerobic ammonium oxidation by anammox bacteria

Abstract.

"Natural abundance of stable nitrogen (N) and oxygen (O) isotopes are invaluable biogeochemical tracers for assessing the N transformations in the environment. To fully exploit these tracers, the N and O isotope effects (15ε and 18ε) associated with the respective nitrogen transformation processes must be known. [...]"

Source: The ISME Journal
Authors: Kanae Kobayashi et al.
DOI: 10.1038/s41396-019-0440-x

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Deep-sea sponge grounds as nutrient sinks: High denitrification rates in boreo-arctic sponges

Abstract.

"Sponges are commonly known as general nutrient providers for the marine ecosystem, recycling organic matter into various forms of bio-available nutrients such as ammonium and nitrate. In this study we challenge this view. We show that nutrient removal through microbial denitrification is a common feature in six cold-water sponge species from boreal and Arctic sponge grounds. [...]"

Source: Biogeosciences
Authors: Christine Rooks et al.
DOI: 10.5194/bg-2019-135

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Nitrogen cycling driven by organic matter export in the South Pacific oxygen minimum zone

Abstract.

"Oxygen minimum zones are expanding globally, and at present account for around 20–40% of oceanic nitrogen loss. Heterotrophic denitrification and anammox—anaerobic ammonium oxidation with nitrite—are responsible for most nitrogen loss in these low-oxygen waters. Anammox is particularly significant in the eastern tropical South Pacific, one of the largest oxygen minimum zones globally. "

Source: Nature Geoscience (2013)
Authors: Tim Kalvelage et al.
DOI: 10.1038/ngeo1739

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Anammox and denitrification in the oxygen minimum zone of the eastern South Pacific

Abstract.

"We quantified the removal of fixed nitrogen as N2 production by anammox and N2 and N2O production by denitrification over a distance of 1900 km along the coasts of Chile and Peru, using short‐term incubations with 15N‐labeled substrates. The eastern South Pacific contains an oxygen minimum zone (OMZ) characterized by an anoxic, nitrate‐ and nitrite‐rich layer of ∼ 200‐m thickness below 30–90 m of oxic water. [...]"

Source: Limnology and Oceanography
Authors: Tage Dalsgaard et al.
DOI: 10.4319/lo.2012.57.5.1331

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Vertical partitioning of nitrogen-loss processes across the oxic-anoxic interface of an oceanic oxygen minimum zone

Abstract.

"We investigated anammox, denitrification and dissimilatory reduction of nitrite to ammonium (DNRA) activity in the Eastern Tropical South Pacific oxygen minimum zone (OMZ) off northern Chile, at high‐depth resolution through the oxycline into the anoxic OMZ core. This was accompanied by high‐resolution nutrient and oxygen profiles to link changes in nitrogen transformation rates to physicochemical characteristics of the water column. Denitrification was detected at most depths, but anammox was the most active N2‐producing process, while DNRA was not detectable. [...]"

Source: Environmental Microbiology
Authors: Loreto De Brabandere et al.
DOI: 10.1111/1462-2920.12255

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Biomarker evidence for the occurrence of anaerobic ammonium oxidation in the eastern Mediterranean Sea during Quaternary and Pliocene sapropel formati

Abstract.

"The eastern Mediterranean Sea sedimentary record is characterised by intervals of organic rich sediment (sapropels), indicating periods of severe anoxia triggered by astronomical forcing. It has been hypothesized that nitrogen fixation was crucial in injecting the Mediterranean Sea with bioavailable nitrogen (N) during sapropel events. However, the evolution of the N biogeochemical cycle of sapropels is poorly understood. For example, the role of the complementary removal reaction, anaerobic ammonium oxidation (anammox), has not been investigated because the traditional lipid biomarkers for anammox, ladderane fatty acids, are not stable over long periods in the sedimentary record. [...]

Source: Biogeosciences
Authors: Darci Rush et al.
DOI: 10.5194/bg-2019-27

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Unexpectedly high diversity of anammox bacteria detected in deep-sea surface sediments of the South China Sea

Abstract.

"Ca. Scalindua is an exclusive genus of anammox bacteria known to exhibit low diversity found in deep-sea ecosystems. In this study, the community composition of anammox bacteria in surface sediments of the South China Sea (SCS) was analyzed using high-throughput sequencing techniques. Results indicated that the dominant OTUs were related to three different genera of anammox bacteria, identified as Ca. Scalindua (87.29%), Ca. Brocadia (10.27%) and Ca. Kuenenia (2.44%), in order of decreasing abundance. [...]"

Source: FEMS Microbiology Ecology
Authors: Jiapeng Wu et al.
DOI: 10.1093/femsec/fiz013

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High denitrification and anaerobic ammonium oxidation contributes to net nitrogen loss in a seagrass ecosystem in the central Red Sea

Abstract.

"Nitrogen loads in coastal areas have increased dramatically, with detrimental consequences for coastal ecosystems. Shallow sediments and seagrass meadows are hotspots for denitrification, favoring N loss. However, atmospheric dinitrogen (N2) fixation has been reported to support seagrass growth. Therefore, the role of coastal marine systems dominated by seagrasses in the net N2 flux remains unclear. Here, we measured denitrification, anaerobic ammonium oxidation (anammox), and N2 fixation in a tropical seagrass (Enhalus acoroides) meadow and the adjacent bare sediment in a coastal lagoon in the central Red Sea. [...]"

Source: Biogeosciences
Authors: Neus Garcias-Bonet et al.
DOI: 10.5194/bg-15-7333-2018

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Single cell genomic and transcriptomic evidence for the use of alternative nitrogen substrates by anammox bacteria

Abstract.

"Anaerobic ammonium oxidation (anammox) contributes substantially to ocean nitrogen loss, particularly in anoxic marine zones (AMZs). Ammonium is scarce in AMZs, raising the hypothesis that organic nitrogen compounds may be ammonium sources for anammox. Biochemical measurements suggest that the organic compounds urea and cyanate can support anammox in AMZs. [...]"

Source: The ISME Journal
Authors: Sangita Ganesh et al.
DOI: 10.1038/s41396-018-0223-9

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The hunt for the most-wanted chemolithoautotrophic spookmicrobes

Abstract.

"Microorganisms are the drivers of biogeochemical methane and nitrogen cycles. Essential roles of chemolithoautotrophic microorganisms in these cycles were predicted long before their identification. Dedicated enrichment procedures, metagenomics surveys and single-cell technologies have enabled the identification of several new groups of most-wanted spookmicrobes, including novel methoxydotrophic methanogens that produce methane from methylated coal compounds and acetoclastic ‘Candidatus Methanothrix paradoxum’, which is active in oxic soils. [...]"

Source: FEMS Microbiology Ecology
Authors: Michiel H in ‘t Zandt et al.
DOI: 10.1093/femsec/fiy064


Vertical segregation among pathways mediating nitrogen loss (N2 and N2O production) across the oxygen gradient in a coastal upwelling ecosystem

Abstract.

"The upwelling system off central Chile (36.5° S) is seasonally subjected to oxygen (O2)-deficient waters, with a strong vertical gradient in O2 (from oxic to anoxic conditions) that spans a few metres (30–50 m interval) over the shelf. This condition inhibits and/or stimulates processes involved in nitrogen (N) removal (e.g. anammox, denitrification, and nitrification). During austral spring (September 2013) and summer (January 2014), the main pathways involved in N loss and its speciation, in the form of N2 and/or N2O, were studied using 15N-tracer incubations, inhibitor assays, and the natural abundance of nitrate isotopes along with hydrographic information. [...]"

Source: Biogeosciences
Authors: Alexander Galán et al.
DOI: 10.5194/bg-14-4795-2017

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Nitrogen losses in sediments of the East China Sea: Spatiotemporal variations, controlling factors and environmental implications

Abstract.

"Global reactive nitrogen (N) has increased dramatically in coastal marine ecosystems over the past decades and caused numerous eco-environmental problems. Coastal marine sediment plays a critical role in N losses via denitrification and anaerobic ammonium oxidation (anammox) and release of nitrous oxide (N2O). However, both the magnitude and contributions of denitrification, anammox, and N2O production in sediments still remain unclear, causing uncertainty in defining the N budget for coastal marine ecosystems. [...]"

Source: Biogeosciences
Authors: Xianbiao Lin et al.
DOI: 10.1002/2017JG004036

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N2 production by the anammox reaction in the anoxic water column of Golfo Dulce, Costa Rica

Abstract.

"In oxygen-depleted zones of the open ocean, and in anoxic basins and fjords, denitrification (the bacterial reduction of nitrate to give N2) is recognized as the only significant process converting fixed nitrogen to gaseous N2. Primary production in the oceans is often limited by the availability of fixed nitrogen such as ammonium or nitrate, and nitrogen-removal processes consequently affect both ecosystem function and global biogeochemical cycles. [...]"

Source: Nature (2003)
Authors: Tage Dalsgaard et al.
DOI: 10.1038/nature01526


Ammonium and nitrite oxidation at nanomolar oxygen concentrations in oxygen minimum zone waters

Abstract.

"A major percentage of fixed nitrogen (N) loss in the oceans occurs within nitrite-rich oxygen minimum zones (OMZs) via denitrification and anammox. It remains unclear to what extent ammonium and nitrite oxidation co-occur, either supplying or competing for substrates involved in nitrogen loss in the OMZ core. Assessment of the oxygen (O2) sensitivity of these processes down to the O2 concentrations present in the OMZ core (<10 nmol⋅L−1) is therefore essential for understanding and modeling nitrogen loss in OMZs. We determined rates of ammonium and nitrite oxidation in the seasonal OMZ off Concepcion, Chile at manipulated O2 levels between 5 nmol⋅L−1 and 20 μmol⋅L−1. [...]"

Source: Proceedings of the National Academy of Sciences of the United States of America (PNAS)
Authors: Laura A. Bristow et al.
DOI: 10.1073/pnas.1600359113

Full article


Fixed-Nitrogen Loss Associated with Sinking Zooplankton Carcasses in a Coastal Oxygen Minimum Zone (Golfo Dulce, Costa Rica)

Abstract.

"Oxygen minimum zones (OMZs) in the ocean are of key importance for pelagic fixed-nitrogen loss (N-loss) through microbial denitrification and anaerobic ammonium oxidation (anammox). Recent studies document that zooplankton is surprisingly abundant in and around OMZs and that the microbial community associated with carcasses of a large copepod species mediates denitrification. Here, we investigate the complex N-cycling associated with sinking zooplankton carcasses exposed to the steep O2 gradient in a coastal OMZ (Golfo Dulce, Costa Rica). 15N-stable-isotope enrichment experiments revealed that the carcasses of abundant copepods and ostracods provide anoxic microbial hotspots in the pelagic zone by hosting intense anaerobic N-cycle activities even in the presence of ambient O2. [...]" 

Source: Frontiers in Marine Science
Authors: Peter Stief et al.
DOI: 10.3389/fmars.2017.00152

Full article


Aerobic and anaerobic ammonium oxidizers in the Cariaco Basin: distributions of major taxa and nitrogen species across the redoxcline

Abstract.

"Depth distributions of cells and functional gene copies from anaerobic ammonium-oxidizing (anammox) bacteria, aerobic ammonium-oxidizing bacteria (AOB) and archaea (AOA) in the Cariaco Basin, Venezuela were obtained using FISH and q-PCR assays. These distributions were compared to concentrations of dissolved ammonium (NH4+), nitrite (NO2-), nitrate (NO3-), hydrogen sulfide (H2S) and oxygen (O2) along the redoxcline during 3 cruises. Cell counts of anammox bacteria and copies of their nitrite reductase gene (Scalindua-nirS) were consistently observed in 2 distinct layers: the suboxic zone (≤1.1 × 106 cells l-1) and the upper euxinic zone (≤4.7 × 106 cells l-1). [...]"

Source: Aquatic Microbial Ecology 79
Authors: Sara Cernadas-Martín et al.
DOI: 10.3354/ame01817

Full article


Seasonal and short-term variation in denitrification and anammox at a coastal station on the Gulf of Finland, Baltic Sea

(January 2008)

Abstract. 

"Benthic processes were measured at a coastal deposition area in the northern Baltic Sea, covering all seasons. The N2 production rates, 90–400μmol Nm−2d−1, were highest in autumn-early winter and lowest in spring. Heterotrophic bacterial production peaked unexpectedly late in the year, indicating that in addition to the temperature, the availability of carbon compounds suitable for the heterotrophic bacteria also plays a major role in regulating the denitrification rate. Anaerobic ammonium oxidation (anammox) was measured in spring and autumn and contributed 10% and 15%, respectively, to the total N2 production. [...]"

Source: Hydrobiologia 596
Authors: Susanna Hietanen & Jorma Kuparinen
DOI: 10.1007/s10750-007-9058-5

Full article


N2 production rates limited by nitrite availability in the Bay of Bengal oxygen minimum zone

Abstract.

A third or more of the fixed nitrogen lost from the oceans as N2 is removed by anaerobic microbial processes in open ocean oxygen minimum zones. These zones have expanded over the past decades, and further anthropogenically induced expansion could accelerate nitrogen loss. However, in the Bay of Bengal there has been no indication of nitrogen loss, although oxygen levels are below the detection level of conventional methods (1 to 2 μM). Here we quantify the abundance of microbial genes associated with N2 production, measure nitrogen transformations in incubations of sampled seawater with isotopically labelled nitrogen compounds and analyse geochemical signatures of these processes in the water column. We find that the Bay of Bengal supports denitrifier and anammox microbial populations, mediating low, but significant N loss.

Source: Nature Geoscience
Authors: L. A. Bristow et al.
DOI: 10.1038/ngeo2847

Read the full article here.


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