Warming stimulates sediment denitrification at the expense of anaerobic ammonium oxidation
"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.
Interactions of anaerobic ammonium oxidizers and sulfide-oxidizing bacteria in a substrate-limited model system mimicking the marine environment
"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.
Environmental controls on bacteriohopanepolyol profiles of benthic microbial mats from Lake Fryxell, Antarctica
"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. [...]"
Authors: Emily D. Matys et al.
Dual nitrogen and oxygen isotope fractionation during anaerobic ammonium oxidation by anammox bacteria
"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.
Deep-sea sponge grounds as nutrient sinks: High denitrification rates in boreo-arctic sponges
"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. [...]"
Authors: Christine Rooks et al.
Nitrogen cycling driven by organic matter export in the South Pacific oxygen minimum zone
"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.
Anammox and denitrification in the oxygen minimum zone of the eastern South Pacific
"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.
Vertical partitioning of nitrogen-loss processes across the oxic-anoxic interface of an oceanic oxygen minimum zone
"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.
Biomarker evidence for the occurrence of anaerobic ammonium oxidation in the eastern Mediterranean Sea during Quaternary and Pliocene sapropel formati
"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. [...]
Authors: Darci Rush et al.
Unexpectedly high diversity of anammox bacteria detected in deep-sea surface sediments of the South China Sea
"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.