Effect of organic exudates of Phaeodactylum tricornutum on the Fe(II) oxidation rate constant

González, Albano; Santana-Casiano, J. M.; González‐Dávila, Melchor; Pérez, Norma

doi:10.7773/cm.v38i1b.1808

Cited by 16 publications

(17 citation statements)

References 51 publications

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“…To this effect, the diatom was harvested in seawater with f/2 nutrients (control seawater) as the reference growth (Fig. 1) in close concordance with recent studies (Vasconcelos and Leal 2008;Gonzá lez et al 2012). At these conditions, the cell density increased from 2 3 10 7 cells L 21 to 5.9 3 10 8 cells L 21 after 8 d of culture.…”

Section: Resultssupporting

confidence: 72%

Variability of the phenolic profile in the diatom Phaeodactylum tricornutum growing under copper and iron stress

Rico

López

Santana-Casiano

et al. 2012

Limnology & Oceanography

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Fourteen phenolic compounds were identified and quantified in extracts derived from in vitro culture of Phaeodactylum tricornutum diatom growing in natural seawater (control) and in natural seawater containing the following added copper (Cu) and iron (Fe) metals: Cu(II) (315 nmol L 21 and 790 nmol L 21 ) and Fe(III) (900 nmol L 21 ). The cell concentration was 471% for the last day of culture (expressed as a percentage of the control) for diatoms exposed to iron, while diatoms exposed to copper showed cell densities of 80% and 52.5% at concentrations of 315 nmol L 21 and 790 nmol L 21 , respectively. Each extract revealed the presence of 14 phenolic compounds, with the exceptions of gallic acid, which was detected only in the iron-enriched diatoms, and quercetin, which was not detected in the control diatom exudates. Significant differences in the phenolic profiles were found depending on the metal added to the culture media. These differences seem to be the response to the different needs of diatoms exposed to copper and iron concentrations. These results show that increasing levels of metal result in a general increase in levels of total phenolic contents

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Section: Resultssupporting

confidence: 72%

Variability of the phenolic profile in the diatom Phaeodactylum tricornutum growing under copper and iron stress

Rico

López

Santana-Casiano

et al. 2012

Limnology & Oceanography

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“…The capacity of organic ligands to form a complex with Fe(III) and to reduce Fe(III) to the bioavailable Fe(II) species in seawater has been studied (van den Berg 1995; Santana-Casiano et al 2000;Rose and Waite 2003). The role of several polyphenols is related to the availability of Fe(II) in solution and the presence of natural exudates also retards the oxidation of Fe(II) (González et al 2012). Santana-Casiano et al (2014) reported that the phenolic compounds exuded from microalgae, such as sinapic acid and (+) catechin, have an influence in iron redox chemistry by favouring the persistence of Fe(II) for their requirements.…”

Section: Discussionmentioning

confidence: 98%

Phenolic profile of Dunaliella tertiolecta growing under high levels of copper and iron

López

Rico

Santana-Casiano

et al. 2015

Environ Sci Pollut Res

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The present study investigates the phenolic profile of exudates and extracts of the green algae Dunaliella tertiolecta, harvested in natural seawater in the absence (control) and in the presence of Cu(II) (315 and 790 nmol L(-1)) and Fe(III) (900 nmol L(-1)) in order to identify and quantify the phenolic compounds produced under metallic stress conditions. The presence of metal ions modifies the growth of cells and changes cell metabolism by producing phenolic compounds adapted to the solution. The use of reversed-phase high-performance liquid chromatography (RP-HPLC) permitted the identification of 14 phenolic constituents. The concentration and type of polyphenols detected in cell extracts and in solution are directly related with the metal and its concentration during growth cultures, achieving 1.4 times higher levels of polyphenols under 790 nmol Cu(II) L(-1) with respect to the control experiments. Microalga excretes polyphenols to be adapted to the environmental conditions. Gentisic acid, (+) catechin and (-) epicatechin, the most prominent phenolic compounds detected in the algae extracts, showed high antioxidant activity in inhibiting 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals. This potent activity may be related to its presence in cells and exudates in high concentrations.

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“…Complex redox cycling, such as the oxidation of reduced Fe(II) as it diffuses upwards, and the reduction of sinking Fe(III)(hydr)oxides occur near the redoxcline (Spencer and Brewer, 1971;Sorokin, 2002b;Yemenicioglu et al, 2006;Dellwig et al, 2010). [L t ] near the redoxcline will have consequences for the redox processes of Fe, since organic ligands are known to influence the oxidation and reduction of Fe (Santana-Casiano et al, 2000;Rijkenberg et al, 2006a;González et al, 2012) (in fact, this effect is used by CLE-aCSV, which change the half-wave potential of metals like Fe by complexing it to for example TAC). Increasing and decreasing oxidation rates of Fe(II) in seawater depend on the nature of the organic matter added (Santana-Casiano et al, 2000Rijkenberg et al, 2006a;González et al, 2012).…”

Section: Sources and Sinks Of Fe And Fe-binding Dissolved Organic Ligmentioning

confidence: 99%

Fe-Binding Dissolved Organic Ligands in the Oxic and Suboxic Waters of the Black Sea

et al. 2016

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In the oxygen-rich layer of the Black Sea, above the permanent halocline, the Fe and nitrate concentrations are low where fluorescence is relatively high, indicating uptake by phytoplankton. In this study we used ligand exchange adsorptive cathodic stripping voltammetry (CLE-aCSV), using 2-(2-Thiazolylazo)-p-cresol (TAC) as measuring ligand, to investigate the role of Fe-binding dissolved organic ligands in keeping Fe in the dissolved phase and potentially biologically available. The conditional stability constant, logK ′ , was between 21 and 22 in most samples, which is on average lower than in ocean water. The Fe-binding dissolved organic ligand concentrations varied between 0.35 and 4.81 nEq of M Fe, which was higher than the dissolved concentration of Fe (DFe) as found in most samples. At two stations ligands were saturated in the surface. At one station ligands were saturated near the oxycline, where ligand concentrations seemed to increase, indicating that they play a role in keeping Fe in the dissolved phase across the redox gradient. At the fluorescence maximum (between 40 and 50 m), the dissolved organic ligand binding capacity (alphaFeL = K ′ * [L ′ ]) of Fe was at its highest while the concentration DFe was at its lowest. Here, we find a statistically significant, positive relationship between fluorescence and the logarithm of alphaFeL, along with fluorescence and the ratio of the total ligand concentration over DFe. These relationships are best explained by phytoplankton utilizing Fe from Fe-binding organic ligands, resulting in an increase in free Fe-binding ligands.

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Effect of organic exudates of Phaeodactylum tricornutum on the Fe(II) oxidation rate constant

Cited by 16 publications

References 51 publications

Variability of the phenolic profile in the diatom Phaeodactylum tricornutum growing under copper and iron stress

Variability of the phenolic profile in the diatom Phaeodactylum tricornutum growing under copper and iron stress

Phenolic profile of Dunaliella tertiolecta growing under high levels of copper and iron

Fe-Binding Dissolved Organic Ligands in the Oxic and Suboxic Waters of the Black Sea

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