Cadmium Adsorption by Chlamydomonas reinhardtii and its Interaction with the Cell Wall Proteins

Heliana Kola; Luis M. Laglera; Nalini Parthasarathy; Kevin J. Wilkinson

doi:10.1071/EN04061

RESEARCH ARTICLE

Previous Next Contents Vol 1(3)

Cadmium Adsorption by Chlamydomonas reinhardtii and its Interaction with the Cell Wall Proteins

Heliana Kola ^A ^B , Luis M. Laglera ^A , Nalini Parthasarathy ^A and Kevin J. Wilkinson ^A ^C

+ Author Affiliations

- Author Affiliations

^A Analytical and Biophysical Environmental Chemistry (CABE), University of Geneva, 1211 Geneva 4, Switzerland.

^B Environmental and Analytical Chemistry, Battelle Geneva Research Center, 1227 Carouge-Geneva, Switzerland.

^C Corresponding author. Email: kevin.wilkinson@cabe.unige.ch

Environmental Chemistry 1(3) 172-179 https://doi.org/10.1071/EN04061
Submitted: 28 July 2004 Accepted: 1 November 2004 Published: 7 December 2004

Environmental Context. In natural waters, trace metals levels are largely controlled by microbiology; organisms take up, metabolize, store, and detoxify the metals. However, aquatic organisms may regulate their own uptake via dynamic processes that result in a system that is far from equilibrium. By examining the model title alga with a battery of techniques, a more realistic assessment of metal uptake and metal regulatory processes could be gained.

Abstract. Cadmium adsorption by a wild type strain of Chlamydomonas reinhardtii and a cell wall-less mutant was quantified as a function of Cd speciation in a well-defined aqueous medium. For both strains, Cd adsorption to the cell surface was not predicted by a single-site (Langmuirian) model. Indeed, no saturation of the cell wall was observed, even for Cd concentrations in excess of 5 × 10⁻³ M. A continual production of Cd binding sites appeared to be responsible for the observed increase of Cd adsorption with time. SDS-page separations and measurements of the protein content of algal supernatants demonstrated that organic matter was released by the algae, both in the presence and absence of Cd. Both the nature (e.g. polysaccharides, proteins) and the quantity of exudate production was influenced by the physicochemistry of the external medium. Measurements using the permeation liquid membrane (PLM) and anodic stripping voltammetry (ASV) demonstrated that dissolved cadmium was rapidly complexed by the organic exudates produced by the algae.

Keywords. : algae — bioavailability — Cd — proteins — speciation

Acknowledgements

The authors acknowledge the fifth European framework BIOSPEC project (EVK1-CT-2001–00005) and the Swiss National Science Foundation (200020–101788) for providing funding for this work. The authors thank S. Waffenschmidt (University of Cologne) and M. Goldschmidt-Clermont (University of Geneva) for providing the CW-2 strains, purified proteins of the W6 layer of the cell wall, wild type C. reinhardtii (2137), as well as other important information on the algal strains. The assistance of M. Martin for the ICP-MS and C. Gehin-Delval for the nitrogen measurements is also appreciated. Critical reviews of a previous draft of the manuscript by I. Worms and D. Simon and discussion with H. P. van Leeuwen were extremely helpful.

References

Cadmium Adsorption by Chlamydomonas reinhardtii and its Interaction with the Cell Wall Proteins

Acknowledgements

Subscriber Login