Reduction of Cr (VI) into Cr (III) by organelles of Chlorella vulgaris in aqueous solution: An organelle-level attempt

Chen, Zunwei; Song, Shufang; Wen, Yuezhong

doi:10.1016/j.scitotenv.2016.07.217

Cited by 31 publications

(5 citation statements)

References 49 publications

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“…The organelles of C. vulgaris not only offered a basement to mechanism of the Cr (VI) reduction, but also provide a new sight for removal of heavy metals from contaminated water. [144] Macro-alga Sargassum cymosum has been used as an electron donor for the reduction of Cr(VI).…”

Section: Phyto Speciesmentioning

confidence: 99%

Recent bioreduction of hexavalent chromium in wastewater treatment: A review

Pradhan

Sukla

Sawyer

et al. 2017

Journal of Industrial and Engineering Chemistry

359

125

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Hexavalent chromium (Cr(VI)) in water is a proven carcinogen to different internal and external organs of the living organisms. There are different human activities incorporated to the anthropogenic sources in the environment enriching Cr(VI) of high concentration in the water system above the regulatory level. The physical, chemical and biological properties of chromium favour the dissolution in the water environment. This concerns the environmental researcher to tackle and mitigate. Chemical or biological techniques or a combination of the two have been used to remove Cr(VI) from polluted waters. Biological techniques include integrated bioremediation, such as the primary processes of direct bioreduction and biosorption, and secondary processes of microbial fuel cell, biostimulation, surface modified dry biomass and biochar adsorption, and engineered biofilm and cell free reductase. These techniques are used by a wide range of living organisms including bacteria, fungi, plants, plant leaves, plant nuts and algae. This group of living organisms transform and remove Cr(VI) from water during the cellular metabolisms, extracellular activities, physical and chemical adsorptions on the cell surface, and photosynthesis. Variation of different physical, chemical and environmental parameters affecting the efficiency of the bioremediation process have impacted on the design of bioreactors. There has been a recent development of a microbial fuel cell which use the proximity of Cr(VI) reduction as a cathode half cell for the generation of renewable energy and simulation of its' removal from water.

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Section: Phyto Speciesmentioning

confidence: 99%

Recent bioreduction of hexavalent chromium in wastewater treatment: A review

Pradhan

Sukla

Sawyer

et al. 2017

Journal of Industrial and Engineering Chemistry

359

125

View full text Add to dashboard Cite

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“…This, in principle, accounts for its phytotoxic effects, inhibition of growth, and degradation of photosynthetic pigments ( Panda and Choudhury, 2005 ). However, details of the mechanisms of the reduction of Cr(VI) to Cr(III) on the organelle level, and in algal chloroplasts, in particular, are still unclear ( Chen et al., 2016 ). Further, the toxicity of chromium can be recognized at several different levels of the structural and functional complexity of the photosynthetic machinery.…”

Section: Introductionmentioning

confidence: 99%

Similarities and Differences in the Effects of Toxic Concentrations of Cadmium and Chromium on the Structure and Functions of Thylakoid Membranes in Chlorella variabilis

et al. 2020

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Trace metal contaminations in natural waters, wetlands, and wastewaters pose serious threats to aquatic ecosystems—mainly via targeting microalgae. In this work, we investigated the effects of toxic amounts of chromium and cadmium ions on the structure and function of the photosynthetic machinery of Chlorella variabilis cells. To halt the propagation of cells, we used high concentrations of Cd and Cr, 50–50 mg L −1 , in the forms of CdCl 2 x 2.5 H 2 O and K 2 Cr 2 O 7 , respectively. Both treatments led to similar, about 50% gradual diminishment of the chlorophyll contents of the cells in 48 h, which was, however, accompanied by a small (~10%) but statistically significant enrichment (Cd) and loss (Cr) of ß-carotene. Both Cd and Cr inhibited the activity of photosystem II (PSII)—but with more severe inhibitions with Cr. On the contrary, the PsbA (D1) protein of PSII and the PsbO protein of the oxygen-evolving complex were retained more in Cr-treated cells than in the presence of Cd. These data and the higher susceptibility of P700 redox transients in Cr-treated cells suggest that, unlike with Cd, PSII is not the main target in the photochemical apparatus. These differences at the level of photochemistry also brought about dissimilarities at higher levels of the structural complexity of the photosynthetic apparatus. Circular dichroism (CD) spectroscopy measurements revealed moderate perturbations in the macro-organization of the protein complexes—with more pronounced decline in Cd-treated cells than in the cells with Cr. Also, as reflected by transmission electron microscopy and small-angle neutron scattering, the thylakoid membranes suffered shrinking and were largely fragmented in Cd-treated cells, whereas no changes could be discerned with Cr. The preservation of integrity of membranes in Cr-treated cells was most probably aided by high proportion of the de-epoxidized xanthophylls, which were absent with Cd. It can thus be concluded that beside strong similarities of the toxic effects of Cr and Cd, the response of the photosynthetic machinery of C. variabilis to these two trace metal ions substantially differ from each other—strongly suggesting different inhibitory and protective mechanisms following the primary toxic events.

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“…Cr(III) is considerably less toxic than Cr(VI) since it cannot penetrate the cell membrane easily (ATSDR, 2012; Chen et al, 2016; Lewalter et al, 1985). Cr(VI) exists as an oxyanion at physiological pH, mainly chromate and dichromate.…”

Section: Introductionmentioning

confidence: 99%

Hexavalent chromium induces reactive oxygen species and impairs the antioxidant power of human erythrocytes and lymphocytes: Decreased metal reducing and free radical quenching ability of the cells

Husain

Mahmood

2017

Toxicol Ind Health

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The toxicity of hexavalent chromium [Cr(VI)] in biological systems is thought to be closely associated with the generation of free radicals and reactive oxygen species. These species are produced when Cr(VI) is reduced to its trivalent form in the cell. This process results in oxidative stress due to an imbalance between the detoxifying ability of the cell and the production of free radicals. We have studied the effect of potassium dichromate (KCrO), a [Cr(VI)] compound, on the antioxidant power of human erythrocytes and lymphocytes under in vitro conditions. Incubation of erythrocytes and lymphocytes with different concentrations of KCrO resulted in a marked dose-dependent decrease in reduced glutathione and an increase in oxidized glutathione and reactive oxygen species levels. The antioxidant power of the cells was decreased, as determined by metal reducing and free radical quenching assays. These results show that [Cr(VI)] upregulates the generation of reactive oxygen species and, as a consequence, the cellular antioxidant defences are compromised. The resulting oxidative stress may contribute to Cr(VI)-induced cellular damage.

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Reduction of Cr (VI) into Cr (III) by organelles of Chlorella vulgaris in aqueous solution: An organelle-level attempt

Cited by 31 publications

References 49 publications

Recent bioreduction of hexavalent chromium in wastewater treatment: A review

Recent bioreduction of hexavalent chromium in wastewater treatment: A review

Similarities and Differences in the Effects of Toxic Concentrations of Cadmium and Chromium on the Structure and Functions of Thylakoid Membranes in Chlorella variabilis

Hexavalent chromium induces reactive oxygen species and impairs the antioxidant power of human erythrocytes and lymphocytes: Decreased metal reducing and free radical quenching ability of the cells

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