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Changes to the amino acid profile and proteome of the tropical freshwater microalga Chlorella sp. in response to copper stress

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posted on 2022-06-24, 06:11 authored by Manisha Shakya, Ewen SilvesterEwen Silvester, Gavin Rees, KH Rajapaksha, P Faou, Aleicia HollandAleicia Holland
Contamination of freshwaters is increasing globally, with microalgae considered one of the most sensitive taxa to metal pollution. Here, we used 72 h bioassays to explore the biochemical effects of copper (Cu) on the amino acid (AA) profile and proteome of Chlorella sp. and advance our understanding of the molecular changes that occur in algal cells during exposure to environmentally realistic Cu concentrations. The Cu concentrations required to inhibit algal growth rate by 10% (EC10) and 50% (EC50) were 1.0 (0.7–1.2) µg L−1 and 2.0 (1.9–2.4) µg L−1, respectively. The AA profile of Chlorella sp. showed increases in glycine and decreases in isoleucine, leucine, valine, and arginine, with increasing Cu. Proteomic analysis revealed the modulation of several proteins involved in energy production pathways, including: photosynthesis, carbon fixation, glycolysis, and oxidative phosphorylation, which likely assists in meeting increased energy demands under Cu-stressed conditions. Copper exposure also caused up-regulation of cellular processes and signalling proteins, and the down-regulation of proteins related to ribosomal structure and protein translation. These changes in biomolecular pathways have direct effects on the AA profile and total protein content and provide an explanation for the observed changes in amino acid profile, cell growth and morphology. This study shows the complex mode of action of Cu on Chlorella under environmentally realistic Cu concentrations and highlights several potential biomarkers for future investigations.


This work was supported by La Trobe University Postgraduate Research Scholarship (LTUPRS) , a La Trobe University Full Fee Research Scholarship (LTUFFRS) and Ph.D. Top-Up scholarship supported by the Murray Darling Basin Joint Governments in association with the Mur-ray-Darling Freshwater Research Centre (MDFRC/CFE) . The assistance of Shimadzu Australasia (Chris Bowen and Rudi Hollander) in devel-oping the LCMS analytical methods used here is greatly appreciated.


Publication Date



Ecotoxicology and Environmental Safety



Article Number

ARTN 113336







Rights Statement

© 2022 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (, which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited, and is not altered, transformed, or built upon in any way.