Dissolved organic carbon reduces uranium toxicity to the unicellular eukaryote Euglena gracilis

Trenfield, Melanie A.; Ng, J. C.; Noller, B. N.; Markich, Scott J.; Dam, Rick A. van

doi:10.1007/s10646-012-0855-x

Cited by 28 publications

(21 citation statements)

References 40 publications

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“…Mechanisms Euglena uses to eliminate the toxic effects of cadmium, chromium mercury and zinc include increased synthesis of heavy metalchelating molecules with thiol groups and phytochelatins, together with metal sequestration into chloroplasts and mitochondria (Aviles et al, 2005;Garcia-Garcia et al, 2014;Lira-Silva et al, 2011;Mendoza-Cozatl et al, 2006). The effect of dissolved organic carbon on uranium toxicity in E. gracilis has also been investigated (Trenfield et al, 2012). Growth of Euglena in heavy metal containing acidic streams and polluted rivers of mining areas by sequestration of heavy metals suggests that these protists can be used as potent tools for bioremediation of heavy metal contaminated waters.…”

Section: Euglena Under Extreme Conditions and As An Organism For Biormentioning

confidence: 99%

Euglenoid flagellates: A multifaceted biotechnology platform

Krajčovič

Vesteg

Schwartzbach

2015

Journal of Biotechnology

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Section: Euglena Under Extreme Conditions and As An Organism For Biormentioning

confidence: 99%

Euglenoid flagellates: A multifaceted biotechnology platform

Krajčovič

Vesteg

Schwartzbach

2015

Journal of Biotechnology

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“…The loss of motility and the rounding of the cells were described as a stress effect related to low pHvalues and/or metal toxicity [30], e.g. uranium [21]. At uranium concentrations > 300 g/L at pH 6 for Euglena gracilis it was observed that the cells changed shape from a healthy, long spindle form to a "tear-drop" or cyst-like Brought to you by | New York University Bobst Library Technical Services Authenticated Download Date | 6/1/15 12:40 PM spherical shape [21].…”

Section: Bioaccumulation Of Uranium By Euglena Cellsmentioning

confidence: 99%

“…However, there was no information provided concerning the reaction mechanisms to immobilize uranium by the Euglena cells. Trenfield et al [21] studied the influence of dissolved organic carbon on uranium toxicity to Euglena gracilis at pH 6. Both groups [19,21], however, did not provide any information on the respective uranium speciation in the surrounding water and associated with Euglena cells.…”

Section: Introductionmentioning

confidence: 99%

Speciation of bioaccumulated uranium(VI) by Euglena mutabilis cells obtained by laser fluorescence spectroscopy

Brockmann¹,

Arnold

Bernhard

2014

Radiochimica Acta

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The ability of Euglena mutabilis cells -a unicellular protozoan with a flexible pellicle, which is typically found in acid mine drainage (AMD) environments -to bioaccumulate uranium under acid conditions was studied in batch sorption experiments at pH 3 and 4 using Na 2 SO 4 and NaClO 4 as background media. It was found that axenic cultures of Euglena mutabilis Schmitz were able to bioaccumulate in 5 days 94.9 to 99.2% of uranium from a 1 × 10 −5 mol/L uranium solution in perchlorate medium and 95.1 to 95.9% in sodium sulfate medium, respectively. The speciation of uranium in solution and uranium bioaccumulated by Euglena mutabilis cells, were studied by laser induced fluorescence spectroscopy (LIFS). The LIFS investigations showed that the uranium speciation in the NaClO 4 systems was dominated by free uranyl(VI) species and that the UO 2 SO 4 species was dominating in the Na 2 SO 4 medium. Fluorescence spectra of the bioaccumulated uranium revealed that aqueous uranium binds to carboxylic and/or (organo)phosphate groups located on the euglenid pellicle or inside the Euglena mutabilis cells.Reduced uranium immobilization rates of 0.93-1.43 mg uranium per g Euglena mutabilis biomass were observed in similar experiments, using sterile filtrated AMD waters containing, 4.4 × 10 −5 mol/L uranium. These lower rates were attributed to competition with other cations for available sorption sites. Additional LIFS measurements, however, showed that the speciation of the bioaccumulated uranium by the Euglena mutabilis cells was found to be identical with the uranium speciation found in the bioaccumulation experiments carried out in Na 2 SO 4 and NaClO 4 media.The results indicate that Euglena mutabilis has the potential to immobilize aqueous uranium under acid condition and thus may be used in future as promising agent for immobilizing uranium in low pH waste water environments.

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“…Alteration of cell morphology of Euglena gracilis under stress was recorded after the exposure to metals such as cadmium, tributyltin chloride and uranium. E. gracilis can change its spindle form to cyst, star and V-shape when the cell is under chemical stress (Ohta M et al 2001;Watanabe and Suzuki 2001;Ohta and Suzuki 2007;Trenfield et al 2012).…”

Section: Euglena Gracilis Z and Smz As In-vivo Modelsmentioning

confidence: 99%

“…Furthermore, CuSO 4 was more toxic to the Z strain than SMZ strain in K-H medium. In both media Z and SMZ cells showed limited toxicity to ZnSO 4 (as a control for zinc-cyanide complex mixed species toxicity) which may be explained by the high concentration of organic matter and glucose in K-H medium which can interfere with metal toxicity (Trenfield et al 2012), or due to the use by specific enzymes of zinc which is an essential micronutrient for eukaryotic cell (Leeson 2009). …”

Section: Comparison Composite and K-h Mediamentioning

confidence: 99%

Toxicity evaluation of copper and zinc cyanide complexes using Euglena gracilis Z and SMZ as an in-vivo model

Al-Saadi¹

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Gold cyanidation is the most used technique worldwide despite cyanide being highly toxic. The reaction of cyanide with metals such as copper and zinc during or after gold recovery builds up moderate and weak metal-cyanide complexes in tailings storage facilities (TSFs) which if not managed may find their way into the environment.Migratory birds and other waterfowl that ingest with the tailings water or waste discharged from cyanidation operations have the potential to cause adverse effects mainly due to the highly toxic free cyanide (HCN + CN -) and free cyanide released from metal-cyanide complexes particularly under acid condition.The International Cyanide Management Code (ICMC) has set 50 mg/L of weak acid dissociable (WAD) cyanide discharge into tailings dam as a protective guideline for birds and biota. However, this guideline value was established based on field observations and is not based directly on scientific toxicological data as identified by NICNAS and this remains a knowledge gap.The toxicity of cyanide and metal-cyanide complexes was assessed using Euglena gracilis strains Z and SMZ. The unique plant-and animal-like properties of Euglena gracilis, and its tolerance to a wide range of pH values including acid pH which is similar to that of the upper gastrointestinal tract of birds where dissociation of metal-cyanide complexes take place, offer a distinct advantage over other algal cells to be selected for this project.Euglena gracilis Z and SMZ strains were exposed to copper sulfate, zinc sulfate, sodium cyanide, copper-and zinc-cyanide complexes mixed species solutions and one tailings sample for 24 h and 48 h. Two methods for the assessment of inhibitory concentration at 50% (IC 50 ) were applied namely an optical density measurement at the absorbance wavelength 610 nm and a modified resazurin assay. The modified resazurin assay provided more robust and reproducible results. Based on a WAD CN molar basis the cytotoxicity data (IC 50 ) for E. gracilis Z in the order of: NaCN (1.24 mg CN/L, 95% CI: 1.03 to 1.5) ~ zinc-cyanide complex mixed species (1.61 mg CN/L, 95% CI:1.3 to 2) > copper-cyanide complex mixed species (4.17 mg CN/L, 95% CI:3.7 to 4.7) and for SMZ cells in the order of NaCN (1.02 mg CN/L, 95% CI:0.91 to 1.1) > zinc-cyanide complex mixed species (2.13 mg CN/L, 95% CI:1.7 to 2.7) > copper-cyanide complex mixed species (5.54 mg CN/L, 95% CI:5 to 6.1), respectively. 2 Further, the chicken was used as a surrogated model for the migratory birds to determine the effects of short-term exposure to sub-lethal doses of sodium cyanide, copper-cyanide complex mixed species, zinc-cyanide complex mixed species and gold mine tailings sample contains less than the ICMC guideline (50 mg WAD CN/L). Based on the CN released it has been found that the toxicity (in chickens) is in the order of: NaCN > zinc-cyanide complex mixed species > copper-cyanide complex mixed species.Calibration of toxicity of NaCN to E. gracilis against chicken showed a good relationship (correlation coefficient R 2 = 0.9...

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Dissolved organic carbon reduces uranium toxicity to the unicellular eukaryote Euglena gracilis

Cited by 28 publications

References 40 publications

Euglenoid flagellates: A multifaceted biotechnology platform

Euglenoid flagellates: A multifaceted biotechnology platform

Speciation of bioaccumulated uranium(VI) by Euglena mutabilis cells obtained by laser fluorescence spectroscopy

Toxicity evaluation of copper and zinc cyanide complexes using Euglena gracilis Z and SMZ as an in-vivo model

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