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Increased metal tolerance and bioaccumulation of zinc and cadmium in Chlamydomonas reinhardtii expressing a AtHMA4 C‐terminal domain protein

Increased metal tolerance and bioaccumulation of zinc and cadmium in Chlamydomonas reinhardtii expressing a AtHMA4 C‐terminal domain protein
Increased metal tolerance and bioaccumulation of zinc and cadmium in Chlamydomonas reinhardtii expressing a AtHMA4 C‐terminal domain protein
The use of microalgal biomass for metal pollutant bioremediation might be improved by genetic engineering to modify the selectivity or capacity of metal biosorption. A plant cadmium (Cd) and zinc (Zn) transporter (AtHMA4) was used as a transgene to increase the ability of Chlamydomonas reinhardtii to tolerate 0.2 mM Cd and 0.3 mM Zn exposure. The transgenic cells showed increased accumulation and internalization of both metals compared to wild‐type. AtHMA4 was expressed either as the full‐length (FL) protein or just the C‐terminal (CT) tail, which is known to have metal‐binding sites. Similar Cd and Zn tolerance and accumulation was observed with expression of either the FL protein or CT domain, suggesting that enhanced metal tolerance was mainly due to increased metal binding rather than metal transport. The effectiveness of the transgenic cells was further examined by immobilization in calcium alginate to generate microalgal beads that could be added to a metal contaminated solution. Immobilization maintained metal tolerance, while AtHMA4‐expressing cells in alginate showed a concentration‐dependent increase in metal biosorption that was significantly greater than alginate beads composed of wild‐type cells. This demonstrates that expressing AtHMA4 FL or CT has great potential as a strategy for bioremediation using microalgal biomass.
Chlamydomonas reinhardtii, bioremediation, cadmium uptake, metal tolerance, zinc uptake
0006-3592
2996-3005
Ibuot, Aniefon
21dbd94f-ba56-4715-bdf1-0163168009fa
Webster, Rachel E.
cbea2f88-9440-48c5-9e38-693c733309c0
Williams, Lorraine E.
79ee1856-3732-492b-8ac5-239749c85d9e
Pittman, Jon K.
186ccb17-c717-43d5-b583-293c7cc986ea
Ibuot, Aniefon
21dbd94f-ba56-4715-bdf1-0163168009fa
Webster, Rachel E.
cbea2f88-9440-48c5-9e38-693c733309c0
Williams, Lorraine E.
79ee1856-3732-492b-8ac5-239749c85d9e
Pittman, Jon K.
186ccb17-c717-43d5-b583-293c7cc986ea

Ibuot, Aniefon, Webster, Rachel E., Williams, Lorraine E. and Pittman, Jon K. (2020) Increased metal tolerance and bioaccumulation of zinc and cadmium in Chlamydomonas reinhardtii expressing a AtHMA4 C‐terminal domain protein. Biotechnology and Bioengineering, 117 (10), 2996-3005. (doi:10.1002/bit.27476).

Record type: Article

Abstract

The use of microalgal biomass for metal pollutant bioremediation might be improved by genetic engineering to modify the selectivity or capacity of metal biosorption. A plant cadmium (Cd) and zinc (Zn) transporter (AtHMA4) was used as a transgene to increase the ability of Chlamydomonas reinhardtii to tolerate 0.2 mM Cd and 0.3 mM Zn exposure. The transgenic cells showed increased accumulation and internalization of both metals compared to wild‐type. AtHMA4 was expressed either as the full‐length (FL) protein or just the C‐terminal (CT) tail, which is known to have metal‐binding sites. Similar Cd and Zn tolerance and accumulation was observed with expression of either the FL protein or CT domain, suggesting that enhanced metal tolerance was mainly due to increased metal binding rather than metal transport. The effectiveness of the transgenic cells was further examined by immobilization in calcium alginate to generate microalgal beads that could be added to a metal contaminated solution. Immobilization maintained metal tolerance, while AtHMA4‐expressing cells in alginate showed a concentration‐dependent increase in metal biosorption that was significantly greater than alginate beads composed of wild‐type cells. This demonstrates that expressing AtHMA4 FL or CT has great potential as a strategy for bioremediation using microalgal biomass.

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More information

Accepted/In Press date: 23 June 2020
e-pub ahead of print date: 24 June 2020
Published date: 1 October 2020
Keywords: Chlamydomonas reinhardtii, bioremediation, cadmium uptake, metal tolerance, zinc uptake

Identifiers

Local EPrints ID: 444751
URI: http://eprints.soton.ac.uk/id/eprint/444751
ISSN: 0006-3592
PURE UUID: d48b5011-31ca-4181-8c54-a90f2046ac8d

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Date deposited: 03 Nov 2020 17:31
Last modified: 21 Nov 2021 21:05

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Contributors

Author: Aniefon Ibuot
Author: Rachel E. Webster
Author: Jon K. Pittman

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