Copper isotope fractionation during excretion from a phototrophic biofilm

Coutaud, Margot; Méheut, Merlin; Viers, Jérôme; Rols, Jean‐Luc; Pokrovsky, Oleg S.

doi:10.1016/j.chemgeo.2019.02.031

Cited by 6 publications

(6 citation statements)

References 91 publications

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“…A small number of studies have investigated Cu isotope fractionation during cellular uptake or cell surface adsorption by microorganisms (Cadiou et al., 2017; Coutaud et al., 2018, 2019; Navarrete et al., 2011; Pokrovsky et al., 2008). The results of these experiments are somewhat variable, with enrichment of either light or heavy Cu isotopes observed during assimilation and adsorption.…”

Section: Coppermentioning

confidence: 99%

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Bioactive Trace Metals and Their Isotopes as Paleoproductivity Proxies: An Assessment Using GEOTRACES‐Era Data

Horner

Little

Conway

et al. 2021

Global Biogeochemical Cycles

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1. What is the modern marine distribution of this TEI system? 104 2. Which biological, chemical, and physical processes are most important for maintaining this 105 distribution? 106 3. In what form is this TEI system incorporated into sediments? 107 4. Are there clear priorities for improving the utility of this system to track paleoproductivity? 108 This structure results in some repetition of the main distributions, drivers, and sedimentary archives 109 between individual TEI systems. This redundancy is deliberate: each section can be read independently 110 without reference to other TEIs. We close our review by assessing the 'maturity' of each system based on 111 a comparison to more established productivity proxies, offer suggestions for future studies, and discuss 112 prospects for paleoproductivity reconstructions using bioactive TEI isotope systems.

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Section: Coppermentioning

confidence: 99%

“…However, assimilation in culture generally favors light Cu isotopes (Cadiou et al., 2017; Navarrete et al., 2011; Figure 13). The complexity in Cu isotopic behavior has been attributed to small changes in Cu speciation or redox during uptake and/or release of Cu (Coutaud et al., 2018, 2019).…”

Section: Coppermentioning

confidence: 99%

Bioactive Trace Metals and Their Isotopes as Paleoproductivity Proxies: An Assessment Using GEOTRACES‐Era Data

Horner

Little

Conway

et al. 2021

Global Biogeochemical Cycles

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“…Zinc and copper isotope analyses in solutions and biological matrices − were performed for the biofilm and the inlet and outlet solutions following the procedure described in previous works of our group, − as described in SI section B. In total, 45 samples corresponding to the Cu and Zn isotopic compositions of the solution and biofilm have been measured.…”

Section: Materials and Methodsmentioning

confidence: 99%

“…The biofilm, as a highly dynamic system, could play a role both as a sink and as a source of trace elements, ,− thus greatly impacting the metal flux in aquatic systems . Copper and zinc interactions with phototrophic biofilms are known to impact the chemical and isotopic fractionation of metals on both short-term (<2 h) and long-term (days) scales. − However, the variation of the metal flux and the degree of associated isotopic fractionation during the photosynthetic cycle of biofilms remain unknown. , The present study is aimed at improving our knowledge of Cu and Zn cycling between the phototrophic biofilm and aqueous solution. Specifically, we focused on identifying possible physicochemical and biological mechanisms responsible for chemical and isotopic fractionation of metals via quantifying the link between metal concentration, fluxes of sorption and excretion, and related isotopic fractionation.…”

Section: Introductionmentioning

confidence: 99%

Elemental and Isotopic Variations of Copper and Zinc Associated with the Diel Activity of Phototrophic Biofilm

Coutaud

Paule

Méheut

et al. 2020

Environ. Sci. Technol.

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The response in metal concentrations and isotopic composition to variations in photosynthetic activity of aquatic micro-organisms is crucially important for understanding the environmental controls on metal fluxes and isotope excursions. Here we studied the impacts of two successive diel cycles on physicochemical parameters, Cu and Zn concentrations, and isotopic composition in solution in the presence of mature phototrophic biofilm in a rotating annular bioreactor. The diel cycles induced fluctuations in temperature, pH, and dissolved oxygen concentration following the variation in the photosynthesis activity of the biofilm. Diel variations in metal concentrations were primarily related to the pH variation, with an increase in metal concentration in solution related to a pH decrease. For both metals, δ( 66 Zn) and δ( 65 Cu) in solution exhibited complex but reproducible diel cycles. Diel variations in photosynthetic activity led to alternatively positive and negative isotope fractionation, producing the sorption of light Zn (Δ( 66 Zn sorbed-solution ) = −0.1 ± 0.06‰) and heavy Cu isotopes (Δ( 65 Cu sorbed-solution ) = +0.17 ± 0.06‰) during the day at high pH and the excretion of lighter Zn isotopes (−0.4‰ < Δ( 66 Zn excreted-biofilm ) < +0.14‰) and heavy Cu isotopes (Δ( 65 Cu excreted-biofilm ) = +0.7 ± 0.3‰) during the night at lower pH. We interpreted Zn and Cu diel cycles as a combination of a desorption of exopolymeric substance−metal complexes and a small active efflux during the night with adsorption and incorporation via an active uptake during the day. The hysteresis of metal concentration in solution over the diel cycle suggested the more important role of uptake compared to desorption and efflux from the biofilm. The phototrophic biofilm presents a non-negligible highly labile metal pool with important potential for contrasting isotopic fractionation at the diel scale.

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“…EPS production is considered as the first protective barrier against toxic substances and, in particular, against metal income into the cells (Pistocchi et al 2000;Sheng and Liu 2011). Extracellular polysaccharides produced by phototrophic biofilms contain acidic sugars that show a high affinity for bivalent metal cations (Rossi et al 2012), suggesting their ability to adsorb and accumulate metal cations and nanoparticles present in the water column (Coutaud et al 2014(Coutaud et al , 2018(Coutaud et al , 2019. However, the secretion of EPS, in response to a stress situation like nutrient limitation, is extremely dependent on the existing environmental conditions (Stewart and Franklin 2008).…”

Section: Introductionmentioning

confidence: 99%

Physiological responses of three mono-species phototrophic biofilms exposed to copper and zinc

Loustau

Ferriol

Koteiche

et al. 2019

Environ Sci Pollut Res

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In freshwater ecosystem, phototrophic biofilms play a crucial role through adsorption and sequestration of organic and inorganic pollutants. However, extracellular polymeric substance (EPS) secretion by phototrophic biofilms exposed to metals is poorly documented. This work evaluated the physiological responses of phototrophic biofilms by exposing three microorganisms (cyanobacterium Phormidium autumnale, diatom Nitzschia palea and green alga Uronema confervicolum) to 20 and 200 μg L −1 of Cu or 60 and 600 μg L −1 of Zn, both individually and in combination. Analysis of metal effects on algal biomass and photosynthetic efficiency showed that metals were toxic at higher concentrations for these two parameters together and that all the strains were more sensitive to Cu than to Zn. U. confervicolum was the most impacted in terms of growth, while P. autumnale was the most impacted in terms of photosynthetic efficiency. In consequence to metal exposure at higher concentrations (Cu200, Zn600 and Cu200Zn600), a higher EPS production was measured in diatom and cyanobacterium biofilms, essentially caused by an overproduction of protein-like polymers. On the other hand, the amount of secreted polysaccharides decreased during metal exposure of the diatom and green alga biofilms. Size exclusion chromatography revealed specific EPS molecular fingerprints in P. autumnale and N. palea biofilms that have secreted different protein-like polymers during their development in the presence of Zn600. These proteins were not detected in the presence of Cu200 despite an increase of proteins in the EPS extracts compared to the control. These results highlight interesting divergent responses between the three monospecies biofilms and suggest that increasing protein production in EPS biofilms may be a fingerprint of natural biofilm against metal pollutants in freshwater rivers.

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Copper isotope fractionation during excretion from a phototrophic biofilm

Cited by 6 publications

References 91 publications

Bioactive Trace Metals and Their Isotopes as Paleoproductivity Proxies: An Assessment Using GEOTRACES‐Era Data

Bioactive Trace Metals and Their Isotopes as Paleoproductivity Proxies: An Assessment Using GEOTRACES‐Era Data

Elemental and Isotopic Variations of Copper and Zinc Associated with the Diel Activity of Phototrophic Biofilm

Physiological responses of three mono-species phototrophic biofilms exposed to copper and zinc

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