Lead accumulation in photosynthetic Euglena gracilis depends on polyphosphates and calcium
Worldwide increasing levels of lead in water systems require the search for efficient ecologically friendly strategies to remove it. Hence, lead accumulation by the free-living algae-like Euglena gracilis and its effects on cellular growth, respiration, photosynthesis, chlorophyll, calcium, and leve...
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Published in | Environmental pollution (1987) Vol. 272; p. 116007 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
England
Elsevier Ltd
01.03.2021
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Subjects | |
Online Access | Get full text |
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Summary: | Worldwide increasing levels of lead in water systems require the search for efficient ecologically friendly strategies to remove it. Hence, lead accumulation by the free-living algae-like Euglena gracilis and its effects on cellular growth, respiration, photosynthesis, chlorophyll, calcium, and levels of thiol- and phosphate-molecules were analyzed. Photosynthetic cells were able to accumulate 4627 mg lead/kgDW after 5 days of culture with 200 μM Pb2+. Nevertheless, exposure to 50, 100 and 200 μM Pb2+ for up to 8 days did not modify growth, viability, chlorophyll content and oxygen consumption/production. Enhanced biosynthesis of thiol molecules and polyphosphates, i.e. the two canonical metal ion chelation mechanisms in E. gracilis, was not induced under such conditions. However, in cells cultured in the absence of phosphate, lead accumulation and polyphosphate content markedly decreased, while culturing in the absence of sulfate did not modify the accumulation of this metal. In turn, the total amount of intracellular calcium slightly increased as the amount of intracellular lead increased, whereas under Ca2+ deficiency lead accumulation doubled. Therefore, the results indicated that E. gracilis is highly resistant to lead through mechanisms mediated by polyphosphates and Ca2+ and can in fact be classified as a lead hyperaccumulator microorganism.
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•E. gracilis is a highly Pb2+ resistant and hyper-accumulating microorganism.•Pb2+ accumulation does not induce synthesis of thiols and polyphosphates molecules.•Pb2+ accumulation depends on polyphosphate content but not on thiol molecules.•Pb2+ exposure does not induce reactive oxygen species production like cadmium.•The absence of Ca2+ promotes increased Pb2+ accumulation. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0269-7491 1873-6424 |
DOI: | 10.1016/j.envpol.2020.116007 |