Inorganic Nutrient Use by Marine Microorganisms

Kirchman, David L.

doi:10.1002/0471263397.env172

Cited by 18 publications

(1 citation statement)

References 119 publications

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“…This is generally consistent with the percentages of 15 N‐DNA of total eukaryotic, bacterial, and archaeal DNA, although each OTU varied in assimilation capability of the four N sources. Ammonium can be utilized directly by metabolic pathways in cells; however,

{NO}_{3}^{-}

needs first to be reduced to

{NH}_{4}^{+}

before utilization, which requires at least five nicotinamide adenine dinucleotides and thus consumes more energy than

{NH}_{4}^{+}

assimilation (Kirchman 2002;). Urea is transported across the cell membrane via adenosine triphosphate‐binding cassette transporters that use energy from adenosine triphosphate and then split into

{NH}_{4}^{+}

and CO 2 by urease (Solomon et al 2010).…”

Section: Discussionmentioning

confidence: 99%

Potential competition between marine heterotrophic prokaryotes and autotrophic picoplankton for nitrogen substrates

Deng

Wang

Wan

et al. 2021

Limnology & Oceanography

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Heterotrophic prokaryotes have the capacity to uptake inorganic nitrogen (N) substrates. However, it remains unclear what the potential competition is between heterotrophic prokaryotes and autotrophic plankton for N in the ocean, which would shunt the flow of N supporting primary production. To date, it has been difficult to distinguish heterotrophic prokaryotic N uptake from that of autotrophic picoplankton, especially in oligotrophic oceans dominated by cyanobacteria. We carried out field-based DNA stable isotope probing incubation experiments in the South China Sea combining measurements of uptake rates of ammonium, nitrate, nitrite, and urea to estimate the taxon-specific potential N assimilation. The results indicate that phylogenetically diverse heterotrophic prokaryotes significantly incorporated multiple N sources, contributing approximately 17-41% and 19-55% of total N uptake potential in the euphotic zone of the South China Sea continental shelf and open ocean, respectively, potentially competing with cyanobacteria (mainly Prochlorococcus). Notably, heterotrophic prokaryotes made a higher contribution to bulk uptake of nitrate in the incubation systems of the open ocean relative to regenerated N, and thus there was a tendency to overestimate the f-ratio. Extrapolating our results to the oligotrophic, low-latitude ocean via a global model suggests the f-ratio would decrease~18%. This suggests a more complicated biogeochemical role of heterotrophic prokaryotes in the biological carbon pump than hitherto assumed, with important implications for N and carbon cycling in the vast open ocean. Nitrogen (N) limits the primary productivity of autotrophic plankton that, together with subsequent carbon export into deeper ocean waters, drives marine carbon sequestration by the so-called biological pump. Ammonium (NH þ 4 ), nitrate (NO À3 ), nitrite (NO À 2 ), and urea are the major nitrogenous substrates ("N substrate[s]" hereinafter only refers to these four substrates) supporting oceanic primary production; thus, measuring their uptake is of primary concern (Mulholland and Lomas 2008). Nitrogen imported into the euphotic zone supports new production, which can be exported into the deep ocean (Eppley and Peterson 1979). The primary source of "new" N to the euphotic zone in the open ocean is thought to be upward diffusion and convection of NO À 3 (Dugdale and Goering 1967). Ammonium and urea are the main N compounds internally recycled within the system, supporting "regenerated" primary production (Dugdale and Goering 1967). Ammonium oxidation and assimilatory reduction of NO À 3 by phytoplankton are two dominant sources of NO À 2 in the euphotic zone (Lomas and Lipschultz 2006;Buchwald and Casciotti 2013) and, therefore, NO À 2 uptake can contribute to new or regenerated primary production.Conventionally, autotrophic plankton are primary consumers of dissolved inorganic nitrogen (DIN) (NH þ 4 , NO À 3 , NO À2 ) in the euphotic zone, while bacterial heterotrophs are primary consumers of organic compounds. However, t...

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{NO}_{3}^{-}

needs first to be reduced to

{NH}_{4}^{+}

before utilization, which requires at least five nicotinamide adenine dinucleotides and thus consumes more energy than

{NH}_{4}^{+}

assimilation (Kirchman 2002;). Urea is transported across the cell membrane via adenosine triphosphate‐binding cassette transporters that use energy from adenosine triphosphate and then split into

{NH}_{4}^{+}

and CO 2 by urease (Solomon et al 2010).…”

Section: Discussionmentioning

confidence: 99%

Potential competition between marine heterotrophic prokaryotes and autotrophic picoplankton for nitrogen substrates

Deng

Wang

Wan

et al. 2021

Limnology & Oceanography

View full text Add to dashboard Cite

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Processes in Microbial Ecology

Kirchman¹

2011

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This book, which discusses the major processes carried out by viruses, bacteria, fungi, protozoa, and other protists – the microbes – in freshwater, marine, and terrestrial ecosystems, focuses on biogeochemical processes, starting with primary production and the initial fixation of carbon into cellular biomass. It then discusses how that carbon is degraded in both oxygen-rich (oxic) and oxygen-deficient (anoxic) environments. These biogeochemical processes are affected by ecological interactions, including competition for limiting nutrients, viral lysis, and predation by various protists in soils and aquatic habitats. The book links up processes occurring at the micron scale to events happening at the global scale, including the carbon cycle and its connection to climate change issues, and ends with a chapter devoted to symbiosis and other relationships between microbes and large organisms. Microbes have large impacts not only on biogeochemical cycles, but also on the ecology and evolution of large organisms, including Homo sapiens.

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2011

Processes in Microbial Ecology

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Inorganic Nutrient Use by Marine Microorganisms

Abstract: The Major Nutrients Trace Elements as Enzyme Cofactors Sodium, Chlorine, Potassium, and Calcium: Osmotic Balance and Salt Bridges

Cited by 18 publications

References 119 publications

Potential competition between marine heterotrophic prokaryotes and autotrophic picoplankton for nitrogen substrates

Potential competition between marine heterotrophic prokaryotes and autotrophic picoplankton for nitrogen substrates

Processes in Microbial Ecology

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