Dissimilatory nitrate reduction to ammonium coupled to Fe(II) oxidation in sediments of a periodically hypoxic estuary

Robertson, Elizabeth K.; Roberts, Keryn L.; Burdorf, Laurine D. W.; Cook, Perran; Thamdrup, Bo

doi:10.1002/lno.10220

Cited by 150 publications

(120 citation statements)

References 74 publications

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“…Most known Fe(II)-oxidizing NO 3 − -reducing microbes live mixotrophically and therefore require an organic carbon source for the oxidation of Fe(II) over a long period (Hansen et al 1996;Straub et al 2004). Recently, researchers confirmed that NO 3 − reduction coupled to Fe(II) oxidation can be catalyzed by microorganisms (Robertson et al 2016). They determined stoichiometries of Fe(II) oxidation and nitrate reduction in microcosm incubations and the incorporation of 14 C from labeled bicarbonate and proved the existence of autotrophic Fe(II)-oxidizing NO 3 − -reducing bacteria in marine sediments.…”

Section: Anaerobic Hcomentioning

confidence: 89%

Thermodynamic energy of anaerobic microbial redox reactions couples elemental biogeochemical cycles

2017

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Purpose The thermodynamic energy of redox reactions affects the distribution of microbial redox reactions and cyclic transformation of elements in various anaerobic ecosystems. The principle of thermodynamics is of dramatic significance in understanding the energetics of metabolic processes, the biogeochemical behavior of microorganisms, and mass and energy cycles. The purpose of this paper is to relate the distribution of the coupling reactions between C, N, Fe, and S, the most important elements involved in microbially mediated redox reactions, with their thermodynamic feasibility to provide theoretical foundation of their occurrence. Results and discussion Anaerobic microorganisms catalyze diverse redox reactions in anoxic environments, driving elemental biogeochemical cycles on the earth. They capture energy from catalyzing these redox reactions in order to support life. The thermodynamic feasibility of these microbe-driven redox reactions is controlled by their energy yields which depend on environmental conditions. Anaerobic microorganisms can oxidize organic carbon with diverse inorganic compounds including nitrate/nitrite, ferric iron, and sulfate as electron acceptors in various anoxic environments which is referred to anaerobic respiration of organic matter; reversely, inorganic carbon can be reduced to synthesize cell material with ferrous iron and sulfide as an alternative electron donor by phototrophs under different sets of circumstances. Nitrate/nitrate can be microbically reduced by inorganic compounds such as ferrous iron and sulfide under some specific situations; the coupling of anaerobic anammox oxidation and reduction of nitrite (anammox), ferric iron (feammox), and sulfate (suramox) driven by anaerobes occurs in other particular systems. Conclusions and perspectives Although there are increasing researches investigating the anaerobe-driven coupling of pairs of elements such as C-N, C-Fe, C-S, N-Fe, N-S, and Fe-S, much more intricate situations associating the coupling of multiple elements are still not comprehensively understood. A great many reactions which are thermodynamically feasible have not yet been identified in natural environments or laboratories. Further work focusing on the metabolic pathways from a genetic and enzymatic perspective and the factors controlling the feasibility of the reactions by using updated technical tools and methods is required.

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Section: Anaerobic Hcomentioning

confidence: 89%

Thermodynamic energy of anaerobic microbial redox reactions couples elemental biogeochemical cycles

2017

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“…Fermentative DNRA consists of the reduction of NO 3 − to NO 2 − to produce energy, and then to NH 4 + to allow reoxidation of NADH 5 (Tiedje, 1988). Chemoautotrophic DNRA consists of the reduction of NO 3 − using sulfide (S -2 ), elemental S, or Fe +2 as electron donors (Robertson et al, 2016;Slobodkina et al, 2017 In fermentative DNRA, the initial reduction of NO 3 − to NO 2 − occurs in the same way as in denitrification and is catalyzed by either the periplasmic nitrate reductase complex (NapAB) or the membrane-bound nitrate reductase complex (NarGHI) (Moreno-Vivián et al, 1999). The reduction of NO 2 − to NH 4 + is catalyzed by the cytochrome C nitrite reductase (NrfA).…”

Section: Dissimilatory Nitrate Reduction To Ammonia (Dnra)mentioning

confidence: 99%

“…The abundance of nrfA genes is correlated with S -2 and Fe 2+ , which can enhance DNRA by providing extra free energy (Robertson et al, 2016;Yin et al, 2017). Elevated temperatures increase DNRA rates; therefore, DNRA may be an important pathway for NO 3 − conversion during summer (Yin et al, 2017).…”

Section: 41mentioning

confidence: 99%

Reviews and syntheses: Processes and functional genes involved in nitrogen cycling in marine environments

Ramos

Pajares

2018

Preprint

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Abstract. Nitrogen is a key element for life in the oceans. It controls primary productivity in many parts of the global ocean, consequently playing a crucial role in the uptake of atmospheric carbon dioxide. The nitrogen cycle is driven by complex biogeochemical transformations mediated by microorganisms, including classical processes such as nitrogen fixation, 10 assimilation, nitrification, denitrification, and dissimilarity nitrate reduction to ammonia, as well as novel processes such as anaerobic ammonium oxidation, comammox and nitrite-driven anaerobic methane oxidation. The nitrogen cycle maintains the functioning of marine ecosystems and will be a crucial component in how the ocean responds to global environmental change. In this review, we summarize the current understanding of the marine microbial nitrogen cycle, its underlying biochemical and enzymatic reactions, the ecology and distribution of the microorganisms involved, and the main impacts of 15 anthropogenic activities.

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“…Reactive Fe minerals, such as oxides, sulfides, phosphates and carbonates, are involved in diagenetic reactions in sediments and consequently influence the cycling of carbon and nutrients (e.g., Berner, 1970;Slomp et al, 1996a,b;Lovley et al, 2004;Jilbert and Slomp, 2013;Kraal et al, 2015;Robertson et al, 2016). Iron has also recently been shown to stabilize organic carbon in sediments, promoting carbon 5 burial (Lalonde et al, 2012;Shields et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, Fe has recently been suggested to play an important role in carbon burial (Lalonde et al, 2012;Shields et al, 2016) and nitrogen cycling (Robertson et al, 2016) in marine sediments. 15…”

Section: Introductionmentioning

confidence: 99%

Flocculation of dissolved organic matter controls the distribution of iron in boreal estuarine sediments

Jilbert¹,

Asmala²,

Schröder³

et al. 2017

Preprint

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Abstract. Iron (Fe) plays a key role in sedimentary diagenetic processes in coastal systems, participating in various redox reactions and influencing the burial of organic carbon. Large amounts of Fe enter the marine environment from boreal river catchments associated with dissolved organic matter (DOM). However, the fate of this Fe pool in estuarine sediments has not been extensively studied. Here we show that flocculation of DOM along salinity gradients in an estuary of the northern Baltic Sea efficiently transfers Fe from the dissolved phase into particulate material that accumulates in the sediments. Consequently, 5we observe a decline with distance offshore in both the Fe content of the sediments and proportion of terrestrial material in the sedimentary organic matter pool. Mössbauer spectroscopy and sequential extractions suggest that large amounts of Fe in sediments of the upper estuarine zone are associated with organic matter as unsulfidized Fe (II) complexes, or present in the form of ferrihydrite, implying a direct transfer of flocculated material to the sediments. Accordingly, the contribution of these components to the total sedimentary Fe declines with distance offshore while other Fe phases become proportionally more 10 important. Sediment core records show that the observed lateral distribution of Fe minerals has remained similar over recent decades, despite variable Fe inputs from anthropogenic sources and eutrophication of the coastal zone. Pore water data suggest that the vertical zonation of diagenetic processes in the sediments is influenced by both the availability of Fe and by bottom water salinity, which controls the availability of sulfate (SO4 2-).

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Dissimilatory nitrate reduction to ammonium coupled to Fe(II) oxidation in sediments of a periodically hypoxic estuary

Cited by 150 publications

References 74 publications

Thermodynamic energy of anaerobic microbial redox reactions couples elemental biogeochemical cycles

Thermodynamic energy of anaerobic microbial redox reactions couples elemental biogeochemical cycles

Reviews and syntheses: Processes and functional genes involved in nitrogen cycling in marine environments

Flocculation of dissolved organic matter controls the distribution of iron in boreal estuarine sediments

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