The oxygen isotope composition of phosphate released from phytic acid by the activity of wheat and &amp;lt;i&amp;gt;Aspergillus niger&amp;lt;/i&amp;gt; phytase

Sperber, Christian von; Tamburini, F.; Brunner, Benjamin; Bernasconi, Stefano M.; Frossard, Emmanuel

doi:10.5194/bg-12-4175-2015

Cited by 37 publications

(43 citation statements)

References 62 publications

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“…For all enzymes studied, the fractionation factors (F) were all positive (Table 5), which are consistent or similar with published results (von Sperber et al, 2015;Wu et al, 2015). This indicates that the heavy 18 O is preferentially incorporated into released P i during enzymatic degradation of phytate by all four enzymes.…”

Section: Isotope Effect: Potential Proxy For Discriminating Enzymes Asupporting

confidence: 90%

“…§ k n,n−1 is the rate coefficient of transformation from IP n to IP n−1 . www.soils.org/publications/sssaj 71 ference for phytate, however, compared with other organic P compounds (e.g., ) is that F is positive for all enzymes studied and is within the range of published results (von Sperber et al, 2015;Wu et al, 2015).…”

Section: Isotopic Composition Of Released Orthophosphate From Phytatesupporting

confidence: 69%

“…Because crude phytase enzyme from wheat contains a large amount of P i and potentially other proteins and enzyme impurities (von Sperber et al, 2015;Wu et al, 2015), it was purified following the Brejnholt et al (2011) method. Briefly, 15 g of crude phytase was dissolved with 0.1 M NaOAc (pH 4.3).…”

Section: Enzyme Purification and Hydrolyzability Assaymentioning

confidence: 99%

“…This could be useful to differentiate the active enzymes for phytate degradation. Because a wide range of fractionation factors have been reported for different substrates as well as enzymes Blake, 2006, 2009;von Sperber et al, 2014von Sperber et al, , 2015, one of the most useful findings that has larger environmental implications is that different enzymes have particular selectivity for phytate degradation and each enzyme has a distinctly different fractionation factor. This distinction opens up the possibility of identifying active phosphohydrolase enzyme(s) responsible for phytate degradation in the environment.…”

Section: Isotope Effect: Potential Proxy For Discriminating Enzymes Amentioning

confidence: 99%

“…Organophosphorus compounds can be hydrolyzed by extracellular phosphatases or other enzymes and subsequently release P i . In the case of enzymatic degradation of phytate, cleavage of a P-O bond linked to the inositol ring incorporates one O from water and inherits three O atoms from the parent phytate molecule in the released P i (von Sperber et al, 2015;Wu et al, 2015). Because the generated P i partially retains the isotope signature of the original phytate, there is a possibility to apply O isotope ratios to trace sources as well as track the fate of phytate in the environment.…”

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confidence: 99%

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Phytate Degradation by Different Phosphohydrolase Enzymes: Contrasting Kinetics, Decay Rates, Pathways, and Isotope Effects

Sun

Alikhani

Massoudieh

et al. 2017

Soil Science Soc of Amer J

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Phytate (IP 6 ) is often the most common organic P compound particularly in agricultural soils. understanding the fate of inositol phosphate (IP x ) in the environment in terms of isomeric composition and concentration and assessing relative resistance to (or preference for) degradation is essential to estimate the potential role of IP x in generating inorganic P (P i ) as well as overall P cycling in the environment. In this study, we analyzed IP 6 degradation by four common phosphohydrolase enzymes (phytase from wheat [Triticum aestivum l.] and Aspergillus niger and acid phosphatase from wheat germ and potato [Solanum tuberosum l.]), with particular focus on degradation pathways, isomer kinetic decay rate, and isotope effects using a combination of high-performance ion chromatography, nuclear magnetic resonance, stable isotopes, and process-based modeling techniques. our results show that the degradation pathways are often distinct among enzymes. The process-based Bayesian inverse modeling was used to capture the trend and magnitude of the measured concentrations for each IP x isomer and to determine the decay constants. Furthermore, o isotope ratios (d 18 o P ) of released P i enabled the identification of isotopically identical phosphate moieties in phytate derived from natural sources. Distinctly different fractionation factors, degradation pathways, and kinetic decay rate coefficients among the enzymes studied could lead to potential discrimination and tracking of phytate sources and products as well as active enzymes present in the environment.Abbreviations: HPIC, high-performance ion chromatography; IP, inositol phosphate; NMR, nuclear magnetic resonance; P i , inorganic phosphorus; pNPP, para-nitrophenyl phosphate.I nositol phosphates are a group of organic P compounds widely present in the natural environment (Turner et al., 2002). Phytate (the salt of myo-inositol 1,2,3,4,5,6-hexakisphosphate or IP 6 ) is a P storage molecule in cereals and grains and represents between 60 and 80% of P in mature seeds (Raboy, 1997). Since it is reported that ?51 million tonnes of phytate is formed in commercially produced fruits and crop seeds every year (Lott et al., 2000), a good fraction of phytate in seeds and grains is released to the soil environment as plant residues and animal manures (Dao, 2007;Gerke, 2015). Phytate readily sorbs onto minerals or precipitates with soil cations and organic matter, and then accumulates to constitute an often dominant class of organic P (Celi and Barberis, 2007;Giles and Cade-Menun, 2014). Although sorption and precipitation immobilizes a large fraction of phytate in soil, there is a potential for its transfer to water bodies with soil particulates and colloids (Turner et al., 2002;Turner and Newman, 2005 Core Ideas• Phytate is degraded through distinct pathways for a particular enzyme.• oxygen isotope ratios of phosphate moieties in phytate are isotopically identical.• These findings bring new insights into tracking phytate sources in the environment.

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Section: Isotope Effect: Potential Proxy For Discriminating Enzymes Asupporting

confidence: 90%

Section: Isotopic Composition Of Released Orthophosphate From Phytatesupporting

confidence: 69%

Section: Enzyme Purification and Hydrolyzability Assaymentioning

confidence: 99%

Section: Isotope Effect: Potential Proxy For Discriminating Enzymes Amentioning

confidence: 99%

mentioning

confidence: 99%

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Phytate Degradation by Different Phosphohydrolase Enzymes: Contrasting Kinetics, Decay Rates, Pathways, and Isotope Effects

Sun

Alikhani

Massoudieh

et al. 2017

Soil Science Soc of Amer J

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Phosphorus availability and turnover in the Chesapeake Bay: Insights from nutrient stoichiometry and phosphate oxygen isotope ratios

Bai

Bear

et al. 2017

JGR Biogeosciences

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Understanding phosphorus (P) availability and its control on eutrophication in the Chesapeake Bay is complicated by variable sources and biogeochemical reactions transforming P forms. We investigated seasonal and spatial variability in P limitation and biological utilization in the Bay using nutrient stoichiometry (of both dissolved and particulate forms), phosphate oxygen isotope ratios, and alkaline phosphatase activity at three sites along the salinity gradient. We demonstrate that particulate nutrient ratios can be used as indicators of nutrient limitation in the Bay and suggest strong seasonal and spatial variability in P availability: the surface water is P limiting in spring, but this condition is alleviated in summer and in the deeper waters. Variability in P limitation is well reflected in the trends of phosphate oxygen isotope composition (δ18OP), with values approaching isotopic equilibrium under P limiting conditions, suggesting rapid biological P turnover. Furthermore δ18OP values suggest multiple phosphate sources including remobilization of terrestrial inorganic P phases and remineralization of organic P and P from both sources is sufficiently cycled by microorganisms, suggested by the extensive equilibrium oxygen isotope exchange. Our results further suggest high P utilization in the deeper euphotic zone where nutrients are abundant, raising caution on studying nutrient availability and limitation only in the surface water.

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δ18O as a tracer of PO43- losses from agricultural landscapes

Hipsey

Gooddy

Reshid

et al. 2022

Preprint

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Accurately tracing the sources and fate of excess PO4 3in waterways is necessary for sustainable catchment management. The natural abundance isotopic composition of O in PO4 3-(δ 18 OP) is a promising tracer of point source pollution, but its ability to track diffuse agricultural pollution is unclear. We tested the hypothesis that δ 18 OP could distinguish between agricultural PO4 3sources by measuring the integrated δ 18 OP composition and P speciation of contrasting inorganic fertilisers (compound v rock) and soil textures (sand, loam, clay). δ 18 OP composition differed between the three soil textures sampled across six working livestock farms: sandy soils had lower overall δ 18 OP values (21 ± 1 ‰) than the loams (23 ± 1 ‰), which corresponded with a smaller, but more readily leachable, PO4 3pool. Fertilisers had greater δ 18 OP variability (~8‰) driven by both fertiliser type and manufacturing year. Upscaling these values showed that 'agricultural soil leaching' δ 18 OP signatures could span from 18 -25 ‰, and are influenced by both fertiliser type and the time between application and leaching. These findings emphasise the potential of δ 18 OP to untangle soilfertiliser P dynamics under controlled conditions, but that its use to trace catchmentscale agricultural PO4 3losses is limited by uncertainties in soil biological P cycling and its associated isotopic fractionation.

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The oxygen isotope composition of phosphate released from phytic acid by the activity of wheat and <i>Aspergillus niger</i> phytase

Cited by 37 publications

References 62 publications

Phytate Degradation by Different Phosphohydrolase Enzymes: Contrasting Kinetics, Decay Rates, Pathways, and Isotope Effects

Phytate Degradation by Different Phosphohydrolase Enzymes: Contrasting Kinetics, Decay Rates, Pathways, and Isotope Effects

Phosphorus availability and turnover in the Chesapeake Bay: Insights from nutrient stoichiometry and phosphate oxygen isotope ratios

δ18O as a tracer of PO43- losses from agricultural landscapes

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