Coupled nitrogen and oxygen isotope fractionation of nitrate during assimilation by cultures of marine phytoplankton

Granger, Julie; Sigman, Daniel M.; Needoba, Joseph A.; Harrison, Paul J.

doi:10.4319/lo.2004.49.5.1763

Cited by 388 publications

(496 citation statements)

References 44 publications

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“…This resulted in N and O isotopic shifts at lower nitrate concentrations that were likely due to the spontaneous decomposition of nitrite to nitric oxide and reoxidation of nitric oxide to nitrate (Granger et al 2006). Consequently, we proceeded to remove nitrite from samples within a few weeks of their collection.…”

Section: Methodsmentioning

confidence: 99%

“…Nitrate isotope analyses-Prior to nitrate N and O isotope analyses, nitrite in the culture samples was removed with ascorbate (Granger et al 2006), because nitrite interferes with nitrate isotope analyses. Thawed samples were first divided into duplicates in sealed serum vials.…”

Section: Methodsmentioning

confidence: 99%

“…The first published ocean depth profile of coupled nitrate N and O isotope ratios from the subarctic Pacific revealed a 1 : 1 covariation of the N and O isotope enrichments associated with nitrate assimilation in the euphotic zone (Casciotti et al 2002). Subsequent lab studies demonstrated that phytoplankton cultures indeed fractionate the N and O isotopes of nitrate with equivalent isotope effects during nitrate assimilation (Granger et al 2004). Measurements of the isotopic composition of nitrate in freshwater and in marine systems suggest that denitrification also imparts proportional heavy atom enrichment on the N and O atoms of nitrate (Lehmann et al 2003;Sigman et al 2005).…”

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confidence: 99%

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Nitrogen and oxygen isotope fractionation during dissimilatory nitrate reduction by denitrifying bacteria

Granger

Sigman

Lehmann

et al. 2008

Limnology & Oceanography

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We report the first measurements of coupled nitrogen (N) and oxygen (O) isotope fractionation of nitrate by laboratory cultures of denitrifying bacteria. Two seawater strains (Pseudomonas stutzeri, Ochrobactrum sp.) and three freshwater strains (Paracoccus denitrificans, Pseudomonas chlororaphis, Rhodobacter sphaeroides) were examined. Among four strains of facultative anaerobic denitrifiers, N and O isotope effects were variable, ranging from 5% to 25%, with evidence for a drop in the isotope effects as nitrate concentrations approached the halfsaturation constant for nitrate transport. O isotope effects were similar to their corresponding N isotope effect, such that the progressive increase in 1] 3 1000), yielded slopes of 0.86 to 1.02, with a mean value of 0.96. R. sphaeroides, a photo-heterotroph that possesses only a periplasmic (nonrespiring) dissimilatory nitrate reductase, showed less variability in nitrate N isotope effects, between 13% and 20%, with a modal value of ,15%. In contrast to the respiratory denitrifiers, R. sphaeroides consistently showed a distinct ratio of d 18 O to d 15 N change of ,0.62. We hypothesize that heavy N and O isotope discrimination during respiratory denitrification occurs during the intracellular reduction of nitrate by the respiratory nitrate reductase, and the observed magnitude of fractionation is likely regulated by the ratio of cellular nitrate efflux relative to uptake. The data for R. sphaeroides are consistent with isotope discrimination directly reflecting the N and O isotope effects of the periplasmic nitrate reductase NAP, without modification by nitrate uptake and efflux.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Nitrogen and oxygen isotope fractionation during dissimilatory nitrate reduction by denitrifying bacteria

Granger

Sigman

Lehmann

et al. 2008

Limnology & Oceanography

Self Cite

397

449

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“…Thus no portion of the O 2 minimum zone (OMZ) was found to be adequately low in [O 2 ] to encourage water column denitrification ($5 mmol L À1 ) [Codispoti et al, 2005]. Granger et al, 2004;Wada and Hattori, 1978;Waser et al, 1998] and in field studies [e.g., Altabet, 2001;Altabet and Francois, 1994;Casciotti et al, 2002].…”

Section: Nutrient and Oxygen Concentrations In The Water Columnmentioning

confidence: 99%

Origin of the deep Bering Sea nitrate deficit: Constraints from the nitrogen and oxygen isotopic composition of water column nitrate and benthic nitrate fluxes

Lehmann¹,

Sigman

McCorkle

et al. 2005

Global Biogeochemical Cycles

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[1] On the basis of the normalization to phosphate, a significant amount of nitrate is missing from the deep Bering Sea (BS). Benthic denitrification has been suggested previously to be the dominant cause for the BS nitrate deficit. We measured water column nitrate 15 N/ 14 N and 18 O/ 16 O as integrative tracers of microbial denitrification, together with pore water-derived benthic nitrate fluxes in the deep BS basin, in order to gain new constraints on the mechanism of fixed nitrogen loss in the BS. The lack of any nitrate isotope enrichment into the deep part of the BS supports the benthic denitrification hypothesis. On the basis of the nitrate deficit in the water column with respect to the adjacent North Pacific and a radiocarbon-derived ventilation age of $50 years, we calculate an average deep BS (>2000 m water depth) sedimentary denitrification rate of $230 mmol N m À2 d À1 (or 1.27 Tg N yr À1 ), more than 3 times higher than high-end estimates of the average global sedimentary denitrification rate for the same depth interval. Pore water-derived estimates of benthic denitrification were variable, and uncertainties in estimates were large. A very high denitrification rate measured from the base of the steep northern slope of the basin suggests that the elevated average sedimentary denitrification rate of the deep Bering calculated from the nitrate deficit is driven by organic matter supply to the base of the continental slope, owing to a combination of high primary productivity in the surface waters along the shelf break and efficient down-slope sediment focusing along the steep continental slopes that characterize the BS.

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“…In order to interpret these measurements, however, the isotope effects for the various sources and sinks of NO 3 À must be known. The isotope effects for NO 3 À uptake by phytoplankton (Needoba et al, 2003;Granger et al, 2004) and NO 2 À production by nitrifying bacteria (Mariotti et al, 1981;Casciotti et al, 2003Casciotti et al, , 2010 are relatively well studied, but there are no data on the isotope effects for ammonia oxidation by AOA.…”

Section: Introductionmentioning

confidence: 99%

Enrichment and characterization of ammonia-oxidizing archaea from the open ocean: phylogeny, physiology and stable isotope fractionation

2011

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Archaeal genes for ammonia oxidation are widespread in the marine environment, but direct physiological evidence for ammonia oxidation by marine archaea is limited. We report the enrichment and characterization of three strains of pelagic ammonia-oxidizing archaea (AOA) from the North Pacific Ocean that have been maintained in laboratory culture for over 3 years. Phylogenetic analyses indicate the three strains belong to a previously identified clade of water column-associated AOA and possess 16S ribosomal RNA genes and ammonia monooxygenase subunit a (amoA) genes highly similar (98-99% identity) to those recovered in DNA and complementary DNA clone libraries from the open ocean. The strains grow in natural seawaterbased liquid medium while stoichiometrically converting ammonia (NH 3 ) to nitrite (NO 2 À ). Ammonia oxidation by the enrichments is only partially inhibited by allylthiourea at concentrations known to completely inhibit cultivated ammonia-oxidizing bacteria. The three strains were used to determine the nitrogen stable isotope effect ( 15 e NH3 ) during archaeal ammonia oxidation, an important parameter for interpreting stable isotope ratios in the environment. Archaeal 15 e NH3 ranged from 13% to 41%, within the range of that previously reported for ammonia-oxidizing bacteria. Despite low amino acid identity between the archaeal and bacterial Amo proteins, their functional diversity as captured by 15 e NH3 is similar.

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Coupled nitrogen and oxygen isotope fractionation of nitrate during assimilation by cultures of marine phytoplankton

Cited by 388 publications

References 44 publications

Nitrogen and oxygen isotope fractionation during dissimilatory nitrate reduction by denitrifying bacteria

Nitrogen and oxygen isotope fractionation during dissimilatory nitrate reduction by denitrifying bacteria

Origin of the deep Bering Sea nitrate deficit: Constraints from the nitrogen and oxygen isotopic composition of water column nitrate and benthic nitrate fluxes

Enrichment and characterization of ammonia-oxidizing archaea from the open ocean: phylogeny, physiology and stable isotope fractionation

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